Anthea Mae Montesclaros

[START OF TRANSCRIPT] Rich Roll:Hey everybody, welcome to the Podcast. Some of you longtime viewers are likely at this point familiar with my obsession with sleep. Well, a huge reason for this is due in no small part to today's guest, an amazing human and one of the world's leading researchers in the field of Sleep Science. His name is Matthew Walker. He's a former professor of Psychiatry at Harvard Medical School and a current professor of Neuroscience and Psychology at UC Berkeley, where he also serves as founder and director of the Center for Human Sleep Science. His book, “Why We Sleep”, is an international smash bestseller. It's an extraordinary evidence based primer on all facets of sleep. It's a read that personally has profoundly impacted me, and I say this without any hyperbole, a must for anyone and everyone looking to live and feel better. Matthew, somebody I've wanted to have on the show for ages and ages, I'm over the moon that he's here today and this conversation might be long. It's three hours long, but fear not, it is utterly, utterly fascinating, essential listening, profound, life altering and everything I hoped it would be. So, please hit that subscribe button, if you haven't already. Thank you and strap in. This is me and Dr. Matthew Walker. Well, Matthew, so delighted to have you here, people who listen or watch the show know well my level of obsession with sleep. I'm going to try to refrain from making it basically an indulgent referendum on my sleep. Dr. Walker:Oh, please do. I know that's great, as well. Rich Roll: I'm sure I will diverge into that at some point because I think it's instructive, but I've been looking forward to this for a very long time, huge fan of the work that you do and it's just a pleasure and an honor to have you here today. Dr. Walker: Well, it's a privilege and a delight to be sitting across from you. And I'm longtime listener, as well. Thankful for all that you do. Rich Roll: Yeah, absolutely. I want to kick off with this, one of the super interesting hypotheses in the book that you purport is this idea that sleep evolved before the brain, hence before wakefulness. The lens through which we think about sleep is sort of in reverse, right? The question shouldn't be why do we sleep? The question is really why are we awake, right? Dr. Walker: Yeah. Rich Roll: Whether or not that's true, I think it's super interesting and instructive to kind of shift that lens, and when you think about it from that perspective, everything seems a little bit different. Dr. Walker: Yeah, it is and I have no good sound evidence for that theory right now, but I think from an evolutionary perspective, the first thing which perplexes me is the idiocy of sleep. When you think of sleep from an evolutionary perspective, firstly, you're not finding a mate, you're not reproducing, you're not caring for your young, you're not foraging for food and worst of all, you're vulnerable to predation. Rich Roll: Not only that, you're an insane person, right? You go through this whole thing, like if you were awake and you were experiencing the states that you experience when you're asleep, you would be institutionalized. Dr. Walker: That's right, and that's what we call dream sleep, which seems to be the normal. But, on any one of those grounds, sleep should have been strongly selected against in the course of evolution. But the fact that sleep has fought its way through on every step of the evolutionary pathway. In fact, if we look back, we can even find sleep like states in earthworms, which are ancient from an evolutionary perspective. In other words, sleep evolved with life itself on this planet. Then, despite all of those trappings, it fought its way through heroically, every step along the evolutionary pathway. In other words, if sleep doesn't serve some absolutely vital set of functions, it's probably the biggest mistake that the evolutionary processes has ever made. Rich Roll: Right. Dr. Walker: We've now realized that it didn't make a spectacular blunder. But that premise that sleep evolved is usually founded on the idea that we were awake and then we evolved to sleep. One thought that crossed my mind, and I was perhaps stupid enough to write it in the book, was I wonder if it's the other way around. Why did we assume that we evolved sleep? Why don't we assume that sleep is the de facto state of all birth life on planet Earth, and it's from sleep that wakefulness emerged and evolved? Now shy of a time capsule or some serious smelling salts, I'm probably not going to be able to go back and figure that out, but I think it's an interesting sort of way to… Rich Roll: Well, the evolutionary advantage of wakefulness is self-evident, right? We need to procreate, we need to feed ourselves, but less obvious is the evolutionary advantage of sleep. It just strikes us as being something that gets in the way as opposed to crucial for all the functions that you kind of go through seriatim in the book. Dr. Walker: I think that's perhaps one of the reasons that people are so misunderstanding of sleep and so understandably neglecting of sleep. Because most people, if you didn't understand what sleep is, you would think, well, my body get some rest and my mind is dormant and nothing could be further from the truth. There is an immense cascade of health benefits, this constellation of nighttime gifts that sleep will provide to your body and every operation of the mind that we know is overhauled, some spectacular things. In fact, during certain stages of sleep, your brain is up to 30% more active than when you're awake. It's so understanding that we would think, well, if I didn't know anything about sleep, surely I can just shave off an hour here or two and it just doesn't work like that. One hour we can think of this incredible global experiment that's performed on well over two billion people across 70 countries twice a year. It's called Daylight Savings Time, and what we've discovered is that in the spring, when we lose just one hour of sleep, there is a 24% increase in heart attacks the following day. Rich Roll: So crazy, and the reverse in the fall, right?. Dr. Walker: Yeah, exactly. I think it's a 21% reduction in heart attack, that’s how fragile we are. Rich Roll: Yet if everybody was sleeping eight hours a night, it would be irrelevant, right? It's less about daylight savings time than it is about our social constructs around when we need to get up and go to work or go to school. Dr. Walker: That's right. Yeah, I think society has firstly stigmatized sleep with this label of laziness that, if you're getting sufficient sleep, you're maybe slothful. Sometimes when I'm at speaking events, people will come up and they'll usually wait right until the end of the line of questions and they'll whisper sort of to me, ‘look I'm one of those people who needs, gosh, probably about eight hours of sleep’, as if this is the worst secret, the most shameful thing that you could ever suggest. I think that's the first issue, but then we're working longer hours and pre-pandemic, commuting times had also increased. And when you think about that, we're leaving the house earlier, we're arriving home later. Nobody wants to short change on time with family or Netflix or whatever it is, so the one thing that gets squeezed like vise grips in the middle of the night is this thing called a full night of sleep. Rich Roll: Yeah, you're almost some kind of punk rock revolutionary. You protect your sleep time, right? It is the one thing that's negotiable or dispensable when you're looking at how you allocate your time. Dr. Walker: That's right, it seems to be and of course, the reality is that sleep, alas, is not an optional lifestyle luxury. It's a non-negotiable biological necessity; it is your life support system. Rich Roll: We all know that the people who say, ‘I only need four hours or I only, I'm fine on five hours’, I've heard you say something along the lines of 0% of people need less than X number of hours. That's all a story that people tell themselves, but it's simply not the case. Dr. Walker: That's right. Yes, I think if you look at the weight of the evidence, the number of people who can survive on five hours of sleep or less without showing any impairment, rounded to a whole number and expressed as a percent of the population is zero. To me, you would ask the question, why do people think that they're doing okay? What we've discovered is that your subjective sense of how well you're doing when you are insufficiently slept is a miserable predictor of objectively how you're doing when you're insufficiently slept. It's a little bit like a drunk driver at a bar. You know, they've had six or seven shots and they pick up their car keys and they say, ‘look, I'm fine to drive home’, and your response is, ‘I know that you think you're fine to drive home, but trust me, objectively, you're in no state’, and it's the same way with a lack of sleep. That's one of the frightening aspects of insufficient sleep that you think you're doing just fine and gradually over time, that deficient form of you becomes the new norm and most people don't go from sleeping eight hours down to five hours. It's this sort of gradual chipping away at their sleep time and they don't realize the version of themselves. A great example of this clinically is in sleep disorders such as sleep apnea. These patients will say to you, “Look, doc, I think I'm fine. I think I'm doing pretty well’, and then you treat the sleep apnea, so they start sleeping better, they’re not snoring; they're not gasping for breath, and within a few weeks, they cannot believe the transformed state of themselves. I had one patient who said, it was as though with the sleep apnea device, I'd come along and I'd wiped a frosted window clear and finally I could see again. Rich Roll: Wow. Dr. Walker: That's the type of mental benefit that you get, and of course physiologically, it's amazing. Rich Roll:Yeah, yeah. I mean, I just know when you're younger, sleep comes easy. As you start to age, it becomes a little bit more fragile and elusive and I found myself having to really be much more intentional about it. The difference between having a good night sleep, where I get my eight hours and, I know that I've been in a sufficient amount of REM state and N-REM deep state, all of that, my whole experience of my life is completely different from those nights where I struggle and wake up and had maybe six and just not so good, like everything from, mentally, emotionally, physically, productivity wise, there is nothing that is not positively impacted by having a really good night of sleep, and yet it's for free. We’ll, get into this later, but replicating that day in, day out becomes tricky. Dr. Walker: Yeah, it is a hard thing, and I think one of the lessons I learned from publishing the book, you know at the time, I think the book came out in 2017 and it took about four years to write, prior to that, sleep was really the neglected stepsister in the health conversation of today. I was so upset by the suffering that was happening in society caused by this global sleep loss epidemic, and as a consequence, I was almost a little bit heavy handed, I think, in sort of dishing out some of these facts, and I have to be honest, I have to speak the truth of the Science, as well, but for certain people, that almost made them sort of more anxious, particularly for people with insomnia who, of course, would come to a book called “Why We Sleep”. But the book wasn't called “How to Cure Your Insomnia”, but I'm sure, of course, they're still going to buy that book. I think I learned my lesson to offer some kind of preface regarding that this book is going to be very triggering and challenging if you don't sleep well. Therefore, when you're not daisy chaining those nights of good sleep, just as you're describing night after the night and you understand the detriments of sleep, it can be concerning and I'm the worst for that. You know, just like you, I can't string it together now. I'm getting older; I’m well in the foothills of middle age. 13:29*Rich Roll: You look fabulous, by the way. Dr. Walker: Thank you, I just turned seventy the other day. It's great. But, I think it's that I feel that anxiety and for me it's terrible because I'm lying in bed awake and realizing that my dorsolateral prefrontal cortex is not shutting down; I'm not releasing this neurochemical. My cardiovascular system is going to be this, and at that point, you're dead in the water for the next two hours. You become the sort of like the Woody Allen. Rich Roll: Yet you're the guy like I'm the guy who's supposed to have this figured out. Dr. Walker: That's right and that just shows you that, even if you have all of this knowledge, biology can still teach you a few lessons. Right? Rich Roll: Well, there's so many directions I want to take this, but I think it probably would be wise to just spend a few minutes talking about sort of defining our terms, like what is sleep like going through the various stages and kind of explaining the terrain. Dr. Walker: Sleep in humans, at least, and most mammals and birds are broadly separated into two main types that you'd mentioned. On the one hand, we have non rapid eye movement sleep or non REM sleep for short and non REM sleep has been further subdivided into four separate stages. In fact, unimaginatively called stages one through four -we're a creative bunch, clearly a sleep researcher-decreasing in the depth of sleep. Stages three and four are those really deep stages of restorative sleep. That's what your sort of sleep tracker would say, that's deep sleep stages one and two, then light sleep and then on the other hand, we have rapid eye movement sleep or REM sleep, named not after the popular Michael Stipe band of the 1980s, but after these strange horizontal shuttling eye movements that occur under the eyelid during this stage. REM sleep is the stage during which we principally dream. That's where you have your most sort of florid, most narrative, hallucinogenic, emotional sort of dreams and it turns out that those two types of sleep, non REM and REM, will play out in this incredible battle for brain domination throughout the night. That sort of cerebral war is going to be won and lost every 90 minutes and then replayed every 90 minutes, at least in humans and that creates the standard cycling architecture of sleep. What's fascinating, though, and we actually still don't quite understand why, is that the ratio balance of those two types of sleep, non REM and REM, and changes across the night. What I mean by that is in the first half of the night, the majority of those 90 minute cycles are comprised of lots of deep non REM sleep, but very little REM sleep. As you push through to the second half of the night now, that seesaw balance will actually shift and instead you get much more rapid eye movement sleep, particularly in the last couple of hours. It's not just important to sort of understand one's sleep, but understanding that structure has implications real life. Let's say, for example, that I normally get my eight hours and we can speak about timing on the clock face and what makes sense for people. But let's say that I'm a guy who goes to bed at 10 and I typically wake up at six, but today I've got an early morning meeting or I want to sort of cut my sleep short to get a jump start on the day to get to the gym. I wake up two hours early, so I wake up at four rather than six. How much sleep have I lost? Well, I've lost two hours from eight hours, so I've lost 25% of my sleep. Well, yes and no. Yes, I've lost 25% of my total sleep, but because REM sleep comes late in the morning, I may have lost 50, 60, maybe even 70% of all of my REM sleep. It's not just sort of academic to understand, even though it's fun for me, but for many people, it does have real world implications. Rich Roll: The complexity of it is fascinating. I mean, sleep really is right up there with outer space in the depths of the ocean in terms of its mysteries. The idea that we're just beginning to learn what's actually going on and it's not a matter of I'm sure you get this question all the time, what's more important, REM sleep or non REM sleep or what? What's the significance of being deprived of one over the other? But it's really the interplay of all of these things and the more complex you realize it to be, it becomes impossible to consider that it's not crucial to all facets of human health. Dr. Walker: That's right. When we go back to that evolutionary story of how detrimental sleep is as a state, I think it is. Let's face it, if there were any stage of sleep that were not important, that Mother Nature could have come in and excised and had you doing all of these benefits of wakefulness that I'm quite sure she would have. What we've learned is that every stage of sleep is important. Different stages of sleep perform different functions for the brain and body at different times of night. I often get that question people will say, ‘how can I get more deep sleep’? ‘How can I get more REM sleep’? I often say, well, why do you want more of that? They say, well, ‘isn't that the good stuff’? and that they're both absolutely critical. Now, I could make a scientific argument that REM sleep could be a little bit more important from a simple mortality state, because there were studies done back in the 1980s with rats and they've actually never been replicated again. I found them difficult to read; I do research in humans, I don't do animal research, and I think they won't be replicated for good reason. What they wanted to do is see if a lack of sleep is deathly, is a lack of sleep fatal? They had three different flavors of the experiment. In the first they took rats and they just deprive them of sleep, night and day after day, night and day after day. What they found is that those rats died within about 20 days. In other words, rats will die as quickly from a lack of food as they will from a lack of sleep; that's how fundamental it is. Then, the two additional flavors of the experiment, they selectively deprive them of either just rapid eye movement sleep so that they could get just non REM or they did the opposite. They just deprived them of non REM and gave them REM. Firstly, both of those were fatal, but what was interesting is that the rats died from REM sleep deprivation within about 30 to 40 days and they died from deep non REM sleep deprivation within about 50 or 60 days. If we want to sort of do a Coke-Pepsi challenge between sort of non REM and REM, which one wins out in the mortality battle, it seems to be REM sleep. To me that's interesting, too. If you'd asked me where I would place my bets, I would have said non REM. The reason is because non REM came first, if you look during the sort of the time course of evolution across phylogeny. Non REM sleep was the first sleep to emerge and it was only when we went from reptiles, amphibians and fish and then there was that bifurcation to birds and then mammals did the evolution of REM sleep emerge. So REM sleep is the new kid on the evolutionary block and furthermore, REM sleep evolved twice independently in birds and mammals, which I find it's fascinating too. To come back to your point, I'm sorry I'm drifting, but all stages of sleep are critical. No one stage of sleep you can do without suffering detriment. Rich Roll: Right, it is fascinating that sleep deprivation is fatal and you talk about this in the book. There used to be before they were outlawed, these contests; people would see how long they could go without sleep. There's one case study that I recall from the book where the guy went mad and then literally, I don't know how long it took him, like ten days or something like that before he passed away. Dr. Walker: Well, there were two things that firstly, you're right, the Guinness Book of Record used to recognize record attempts at insufficient sleep. Then as the evidence mounted as to how deleterious a lack of sleep is, they found it medically impossible to recognize and ethically impossible to recognize. Guinness no longer recognizes any attempt to break the world record for a lack of sleep. To put that in context, we think of Felix Baumgartner, that incredible Austrian who went up in the red bolts of space capsule, as it were. When he ascended the outer atmosphere of the planet, he opened up his door and he leapt out and then he hurtled back down to earth. I believe he broke the sound barrier with his own body. Now, Guinness says that's fine, but depriving yourself of sleep? No. That's the relative sort of aspect that have asked that we're thinking about. Rich Roll: Yeah. Dr. Walker: There was a famous case of a radio disc jockey in New York in the 1950s called Peter Tripp, and he wanted to try and break the world record, which was going eight days straight without sleep and he was doing this for the March of Dimes. He would sit in Times Square and he was going to do this place and his records. After three days, he was hallucinating and he was psychotic. After five days, he believed that people were trying to poison him and that the Secret Service was coming to get him. Then he did apparently break the world record, he went eight days straight without sleep, and then he slept for a little over 20 hours. He woke up, he ordered his papers, had his breakfast, and people said, ‘Oh, it seems to be back to normal’. But Tripp was no longer Tripp after that, he started to have problems at work. He got caught up in what was called the payola scandal, where people were sort of paying DJs under the desk to play their tracks. His marriage fell apart and the last people heard was that he was selling books door to door in the Midwest. Rich Roll: Wow, you're attributing that to this crazy experiment that he did? Dr. Walker: Well, that was the belief. Now, other people, I should note, have gone past his level of sleep deprivation. Although they went through the same experience during the lack of sleep psychosis, memory loss, emotional instability, they seem to go back to normal. I think what's happening here, I'm sure we'll come on to sleep and mental health at some point. In those people who are in that vulnerable range, whether they haven't crossed the threshold of mental ill health, but they're right there and anything that pushes them past it be a traumatic event, be it a difficult divorce or a long stretch of no sleep, can actually pull that trigger and send them over that sort of teetering precipice down into a state of prolonged mental ill health. Rich Roll: Right. That's wild. But those are kind of fringe cases in the sense that people are doing this wacky kind of thing. But the more relatable prevalent situation is chronic sleep deprivation, which I don't know what the statistics are. I'm sure you do. Of how many people just on a day in, day out basis are not getting enough sleep and how that plays out long term in terms of their physical, mental, emotional health. Dr. Walker: Yeah, it's quite shocking and I guess this is sort of the insomnia disclaimer if you got to sort of listen away. But firstly, what we know is that one out of every three people that you pass on the street is not getting the sleep that they need. The CDC right now recommends stipulate a minimum of seven hours of sleep to maintain human health. As you said, most people are not pulling all nighters frequently or trying to break world records, but it doesn't take that. We've already mentioned the daylight savings experiment. I'll just give you a few other examples. If I take a healthy young male and I limit them to, let's say, four or five hours of sleep for a couple of nights, their level of testosterone drops to someone who is 10 years their senior. A lack of sleep well age a man by a decade in terms of that critical aspect of wellness and and virility. We see equivalent impairments in female reproductive health, by the way, follicular stimulating hormone, abnormal menstrual cycles, difficulty in conceiving. That's hormones that go awry. We also know, for example, that if I were to take you and put you on a diet of, let's just say, four hours of sleep a night for a couple of nights, at the end of those four nights, your blood sugar levels would be so disrupted that your doctor would classify as being pre-diabetic. Rich Roll: That's crazy. Dr. Walker: Which stuns me and to induce that kind of a deficit, a 40% deficit. In your sort of glucose optimization, you would have to gain about 20 pounds of obese mass within four days, or you could do it by under sleeping. Rich Roll: Wow. Dr. Walker: We also know, for example, that if you're not getting sufficient sleep in the week before you get your flu shot, you produce less than 50% of the normal antibody response. I'm sure we'll discuss that when we speak about immunity. There was a there was an amazing experiment that were done by some colleagues in the United Kingdom, and they put healthy participants through two different conditions. In one condition, they were limited to six hours of sleep a night for one week, and then they were given a full eight hour opportunity for one week. Then they measured the change in their gene activity profile relative to when they were getting sufficient sleep. There were two striking findings; the first was that a sizable and significant 711 genes were distorted in their activity caused by that lack of sleep and this is not dramatic sleep. Rich Roll: I mean, most six hours of six hours. I'm good. That's pretty good. Dr. Walker: Right, that just doesn't seem to be the case biologically. What was also interesting, however, was that about half of those genes were actually increased in their activity or what we call overexpressed. The other half were decreased or switched off in their activity. Now, those genes that were suppressed, caused by a lack of sleep, were numerous genes associated with your immune system. Yet those genes that were actually increased in their activity were genes that were associated with the promotion of tumors, genes that were associated with cellular stress, and as a consequence, cardiovascular disease and genes that were associated also with metabolism and changes in metabolism. What that study taught me, at least, is that there is no aspect of our physiology that seems to be able to retreat at the sign of sleep deprivation and get away unscathed. Rich Roll: Yeah, one of the striking things in the book that really hit me was the relative lack of elasticity in the human body in that just one night of dysregulated sleep a week has much more of a profound deleterious effect than you would think. You would think like well, I pretty well sleep most nights. But once a week my stuff got screwed up but, I'll recover. But the downstream implications of just a little bit of dysregulation are much more serious than one would suspect. Dr. Walker: Yeah, I mean, a good example is another study where if you take healthy adults and you limit them to just four hours of sleep for a single night, the next day we see a 70% drop in critical anticancer fighting among themselves called natural killer cells. Now, today, you and I have both produced cancer cells more than likely. What prevents those cells from becoming and manifesting as the condition that we call cancer is in part these critical cancer fighting immune cells, natural killer cells. That is a dramatic stage of immune deficiency and it happens quickly after just one bad night of sleep, so you could imagine the state of your immune system after weeks, if not months, of insufficient sleep. Rich Roll: Sorry to interrupt the flow. We'll be right back with more awesome, but I want to snag a moment to talk to you about the importance of nutrition. The thing is, most people I know actually already know how to eat better and aspire to incorporate more whole plants, more fruits, vegetables, seeds, beans and legumes into their daily routine. 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This is life changing stuff people, for just a dollar seventy a week, literally the price of a cup of coffee. Again, that's MEALS.RICHROLL.COM promo code RRHEALTH for ten dollars off on annual membership. All right. Let's get back to the show. Rich Roll: Yeah, one of the things that is very vivid in the book as well is this process that takes place when you're sleeping, this kind of detoxification process, right? Where you're kind of cleansing the brain and washing out the beta amyloid and all the kind of negative things that accumulate in the mind throughout the day because wakefulness is really the toxic state, right? Sleep is the restorative state, obviously. You likened it to the island of Manhattan where all the skyscrapers shrink and like a wave washes over them and cleans all of them. All this nasty stuff that we don't want is washed away and when you impede that process, those things start to accumulate, right? That's why we see so many of these downstream, diseases cropping up, everything from Alzheimer's, diabetes, cardiovascular disease, et cetera. Dr. Walker: Yeah, I mean, from the perspective of your brain this sounds a little bit extreme. But biologically, I think it's accurate that wakefulness is low level brain damage and sleep is sanitary salvation. This, I think, is one of the most exciting areas in sleep science over the past five years. It's just ballooned. We've been fortunate enough to do some of this work, which is the relationship between a lack of sleep and Alzheimer's disease. It really is has become a four part story, which is association, causation, mechanism, and then treatment hope. What we understood about four or five years ago is that people who are typically sleeping less than six hours a night went on to develop far more of those sticky, toxic protein elements that are the culprits underlying Alzheimer's disease called beta amyloid and more recently, this thing called tau protein, though, the two proteins that we believe underlie the condition of Alzheimer's disease. Then what we also found is that people who have sleep disorders, such as insomnia or sleep apnea, also have a significantly higher risk of going on to develop Alzheimer's disease later in life. But they're just associations, they don't prove causality. Then several years after that, scientists demonstrated that if you take a healthy adult and you deprive them of sleep for just one night or you deprive them of just deep sleep for one night, you see an immediate escalation in that Alzheimer's protein, beta amyloid circulating in the bloodstream, circulating in the cerebrospinal fluid and also within the brain itself using brain imaging technology. That proved causality that you can take an otherwise healthy person, take away that thing called sleep, and you can trigger that instigation of what seems to be like the emergence of an Alzheimer's cascade in pathology. If that's true, then we ask the question, well, what is it about sleep that deescalates that Alzheimer's disease protein in the brain? I think its Nobel Prize worthy, but a researcher called me Conetta God at the University of Rochester made three remarkable discoveries. She was looking at mice and what happened when they slept and the first thing that she discovered is that the brain has a cleansing system and we didn't think it did. Now, we knew that the body had its own cleansing system, which everyone will know about, called the lymphatic system. But we didn't think the brain did and she discovered, in fact, it does have a cleansing system called the lymphatic system, named after the glial cells that make up this this process. Rich Roll: Right. Those live in between the brain cells, right? Dr. Walker: That's right. Glial is sort of if you look at the Latin and Greek sort of derivative, the entomology is the glue, because we used to think that they were just the cells that kind of glued the actual brain cells, though. Well, they're all brain cells technically, but would glue the neurons together. But they sort of outnumber your neurons by many fold and they're critical. They perform lots of functions, but they form this network, the sewage system, that was the first discovery, then she found that cleansing system wasn't always switched on in high flow volume across the 24 hour period. Instead, it was when those mice were asleep and when they went into deep sleep that sewage system really kicked into high gear. The final discovery, and that's what makes it relevant to Alzheimer's disease is that she found that one of the metabolic byproducts, one of the pieces of metabolic detritus that sleep was washing away was this toxic protein of beta amyloid. Just last year, scientists in Boston actually found a very similar pulsing cleansing mechanism in human beings. That was a mechanism that helped us realize how this could all connect together. For me though, it may all sound very depressing, just as you mentioned yourself and I experienced this, the older that we get, typically the worse I sleep, the older that we get, the greater our risk of Alzheimer's disease. It may sound quite a depressing story, but I think there's a silver lining here, because unlike many of the other factors that are associated with aging and Alzheimer's disease, for example, changes in the physical structure of the brain or even changes in the blood flow dynamics of the brain, that fiendishly difficult to treat. In medicine, we have no good wholesale approaches but that sleep is a missing piece in the explanatory puzzle of aging and Alzheimer's disease is exciting because maybe we can do something about it. Perhaps what we could do is in midlife, which is when we start to see the decline of deep sleep, that's when we could intervene with optimization of sleep, with lots of different methods that are being developed. In that way, could we bend the arrow of Alzheimer's disease risk down on itself? Could we shift from a model of what we have right now, which is late stage treatment to midlife prevention going from a model of sick care to actually health care? That's one of our sort of moonshot goals. I'm incredibly excited. Rich Roll: Yeah, I mean, that's the Holy Grail, right? I think about this all the time when I wake up after an amazing night of sleep and then my experience throughout the day is optimal. Then the following night I have a degraded version of that and I wake up and I think, why can't we figure out a way to replicate this day in and day out without pharmaceutical intervention? Like, I'm trying to do all the right things and yet it is so elusive. Part of that yes is age, because when you're a teenager, you can just fall asleep in an instant and seem to get a good night's sleep no matter what. But I'm constantly thinking about, how do you figure this out and master it? Because if you could, it would literally change everybody's lives. Dr. Walker: If you take the reverse of that, we know starting with this recommended the sweet spot of between seven to nine hours a night going in the downward direction, there's a very simple truth, which is that the shorter your sleep, the shorter your life. Short sleep predicts or cause mortality, right? Rich Roll: Which is so ironic, given that the hustle culture. It's all about maximizing those daylight hours and I'll sleep when I'm dead. That's marketing, not death. Dr. Walker: Yeah, it's mostly unwise advice anyone who tells you that. But to me, I think, sleep could be seen as the Swiss Army Knife of health, whatever ailment that you're facing, sleep normally has a tool in the box that can help. For me, I think the Shangri-La is perhaps less about trying to elongate lifespan than it is really about prolonging people's health span. Because when you ask most people, that's what they really want when they're trying to live a clean, healthy lifestyle they don't want a life with disease and sickness. But when you are starting to short change your brain and your body of sleep, that's what you're inviting. The elastic band of sleep deprivation will stretch only so far before it snaps. If you fight biology, normally you lose and the way you know you've lost is disease. Rich Roll: Yeah, that the human hubris over all of this, though, is something to behold because we always think we can find, an end run around these things. As beautiful and magnificent as the scientific method is, it tends to be very binary in its approach. Right, if X, then Y controlling for variables. But when you're dealing with systems that are so complex, my sense is that oftentimes it leads to unintended negative consequences, right? Like the pill and you'll sleep well but we're not realizing or looking at all these other things that are occurring. It isn't until much later when researchers like yourself can pull the covers on that and say this was not such a good idea. Dr. Walker:Yeah, pull the covers now, no pun intended. But I think you're right, there is a very understandable again, I don't want to sort of be finger wagging or chastise people if you don't know the science of sleep, I would be just as unknowing. But it took Mother Nature 3.6 million years to put this essential thing called, a seven to nine hour sleep need in place to think that with hubris or arrogance that we could come along and within five or 10 years, if we're sort of forcing medical residents to go through these ridiculous sort of schedules or if you're in some other professional industry that you can just find a way to hack that system is unfortunately is misfounded. Rich Roll: The stuff that you said about Alzheimer's and dementia makes a lot of sense, but how does that work with cardiovascular disease? I mean, obviously, brain health is vascular health and heart health certainly is vascular health. But what is the relationship between sleep quality and taking an insurance policy out against heart disease? Dr. Walker: Yeah, I mean, so we mentioned the Daylight Savings Time example. But more than that, we know that people who are typically sleeping less than six hours a night on average will have about a 200% increased risk of cardiovascular disease or a heart attack in their lifetime. We also know from a prospective study that came out of Harvard Medical School that they took a large range of people who had no preexisting signs of cardiovascular disease, and then they tracked them across five or six years. What they found is that those people who are sleeping less than six hours a night, they had a 200% to 300% increased risk of calcification of the coronary artery. The coronary artery is essentially that's the, corridor of life for your heart. When you hear people saying, gosh, they had a massive coronary, what they mean is that coronary artery had become blocked calcification and that's exactly what we see. Now again this was a prospective study. No one had any signs of that before but when you looked at that sleep shaving, sleep coming down and down, that was the predictive factor. We also know that, sort of turning the tables in the positive, why does sleep give you that benefit during deep sleep our heart rate decelerates, our vascular system of vessels start to relax. You can think of deep sleep like the very best form of blood pressure medication that you could ever wish for. We also see that it's during that nighttime phase when we drop levels of cortisol, which otherwise if left in high concentrations of stress-related chemical; it's an adaptive chemical too. We all need cortisol, but if you're just chronically high in cortisol that is deathly for your cardiovascular system and sleep will actually ratchet down that level. Also, sleep will quiet the fight or flight branch of your nervous system. It's called the sympathetic nervous system, which I think is terribly named. It's anything but sympathetic; it's agitating, it's aggravating, and it's during deep sleep that we actually shift over from that fight or flight branch to the more quiescent coming branch called the parasympathetic nervous system. Now, we can start to understand why we see risks for heart attack, risks for cardiovascular disorder. We published the paper a couple of months ago demonstrating that short sleep, and particularly not just short sleep, but also fragmented sleep. This is, I think, another important point that we've learned in the most recent years. It's not just about the quantity of sleep, it's also about the quality of that sleep. We found that people who had fragmented sleep had a higher likelihood of their blood vessels becoming hard to what we call atherosclerosis, the hardening of the blood vessels, which can then be a direct pathway to cardiovascular disease and heart attack as well. Rich Roll: That's interesting. Is there a sense of where that falls in the pecking order of importance when you compare it to nutrition or exercise or these other kind of contributing or ameliorating factors with respect to heart disease? Dr. Walker: It's just as heavy hitter. If you look at the combination of quantity and quality of sleep and you look at the effect sizes, it’s right up there, you can almost play the game. I don't mean to do this because I'm someone who pays. I'm very dedicated to a practice of physical activity and exercise. I'm not quite at your level, but and I eat very cleanly. I too, I'm a vegetarian, so I respect those things because I know how utterly important they are for my health spending my life span, but I can do a thought experiment where I say I take you Rich Roll and I'm going to deprive you of either exercise for 24 hours, of food for 24 hours, of water for 24 hours, or of sleep for 24 hours. Rich Roll: Yeah, I know. Dr. Walker: There's no comparison by a country mile will dwarf the physiological and mental deficits that come by way of that. I think the only other thing that's perhaps will overtake sleep is oxygen. If I stop your function, you will. I hold my hands up, I lose out to oxygen, right? Rich Roll: But you've said often that when you think of the pillars of health, sleep isn't a pillar. It's the foundation upon which all these other pillars are erected, essentially. Dr. Walker: Right. Yeah. I used to think about it. But then, the more I've done this research over the years, the more I realized that I was wrong. It is a foundation on which those the two things said I can give you a good example if you're trying to manage your weight, if you're trying to diet, let's say, and lose weight, but you're not getting sufficient sleep, 70% of all the weight that you lose will come from lean muscle mass and not fat. Rich Roll: Right. The body, when it's fatigued in that way, wants to hold on to those fat circling. Dr. Walker: Exactly, you become stingy in giving up its fat. In other words, when you are under slept, but you're trying to watch your diet, watch what you eat, you will lose what you wanted to keep, which is muscle. You will gain what you wanted to lose, which is fat. Rich Roll: Right. On top of that is when those crazy cravings for terrible foods happen, right? I just know when I'm under slept, that's when I start thinking about all these foods that I shouldn't eat. Dr. Walker: It comes by way of two different routes that are non-mutually exclusive. One is a brain route; the other is a body route. What we firstly discovered when you’re not getting sufficient sleep be it six hours a night, five hours a night, four hours a night for several nights. There are two critical appetite-regulating hormones; these hormones are leptin and ghrelin. I sometimes joke that they sound like hobbits but that’s just my British talking obsession. Leptin is the hormone of satiety; when you release leptin it says to your brain and body “you’re full with what you have just eaten. You don’t want to eat anymore; you’re no longer hungry”. Ghrelin is the opposite. Ghrelin is the hunger hormone. It says no; you’re not satisfied with your food and you want to eat more. When you are under slept, those hormones go in the opposite direction, in ways you don’t wish them to. Firstly, leptin which is the satiety signal, that drops away so you lose that signal of being full and you constantly feel hungry. If that weren’t bad enough by itself, ghrelin - the hunger hormone, that actually increases. Now, you may have eaten a standard meal, that normally otherwise would have been satisfying. But it doesn’t feel satisfying and you still want to eat more. On average, people would typically eat anywhere between two to four hundred extra calories each day under these conditions of insufficient sleep. What was also striking from these studies, is not just that you want to eat more, which in general you do, and you want to snack more, but it's what it is that you have a craving for. Because when you are under slept, you have this increase a particularly a dominant increase in wanting to eat those heavy hitting carbohydrates, also sugars as well as salty snacks. All of those are foods that we know in excess will put you on a path toward this obesogenic profile. Rich Roll: Right. It would be interesting to take a look at whether or not the rate of people going to the drive thru increases on daylight savings, right? On that day when everybody's lost an hour of sleep, they're a little bit more tired. I would suspect it would follow that a lot of people are hit McDonald's on the way to work. Dr. Walker: I wish I could get that data. I wish there was like a McDonald's app where I could look at the usage statistics and then do that study. In the body that's part of the reason but in the brain there is also a pathway. We did a study several years ago where we took a group of healthy adults of normative weight and we either gave them a full night of sleep or we took sleep away for a night and then we put them and same individuals. It's the same people going through two different studies. Inside of the brain scanner, we were showing them these different food items and they had to rate how desirable those food items were. We made this a little bit more real by saying, look, at the end of this brain scan, we're going to pull you out. We’re going to give you one of those foods so that you have to eat it. They're not just saying, oh, OK, I should just be good and I know that I should say is nice. What we found firstly is that people when they were under slept, their hunger increased. Secondly, what we found is that they were rating junk foods as far more desirable as a consequence. Then when we looked at the brain scan, something fascinating happened; there were the deep hedonic emotional centers of the brain. They were revved up as a consequence of a lack of sleep, the sort of impulsive sort of almost these addictive brain centers. In fact, they are a part of the same senses that go awry in addiction. What was also interesting is that other parts of the brain, particularly a part right upstairs above your eyes in the frontal lobe that had shut down, which normally keeps off hedonic desires in check. As a consequence, the under slept people were no longer reaching for leafy greens and a handful of nuts. They were reaching for ice cream, pizzas, the salty snacks, et cetera so, it's both within your brain. That explains why for a fact when I'm not sleeping, I'm always hungry. I can never get satisfied. I can never get full. I don't know why it is brain and body. Rich Roll: Well, I see. I feel seen and heard because as somebody who's been in recovery for a long time in an end of one experiment, I know when I'm under slept or I've had a terrible night of sleep. All of those kind of addictive compulsions because I have some self-awareness around them, I'm able to understand that's what's happening. But it's always been confusing that it correlates. Like, why do I feel like acting out or eating this thing or like sending the email I shouldn't send or all of these things that happen when I'm when I'm under slept. That's very interesting. Dr. Walker: Thanks for bringing that up to about addiction disorders. We've done a little bit of work in this area, too. What we found is that when we shortchange someone's sleep, these dopamine centers within the brain that are what we think of as reward based sensors and the sensors in the brain, that addiction will hijack, those become increased in the sensitivity. Your reward sensitivity increases, your risk taking increases, your impulsivity increases. What we know is that those people who are under slept are far more likely to develop an addiction disorder during use. We also know and this is perhaps even stronger of a relationship when you are trying to abstain and go through recovery. Sleep is a huge predictive factor. When you're getting enough sleep, your chances of remitting and recovering are far higher than when you're not getting sufficient sleep. Rich Roll: Yeah, that makes sense. Well, this is a good opportunity for me to indulge you my own history here. Yeah, because just reading your book again and getting ready for today, I started thinking more profoundly and deeply about my own history with sleep over the years. I had this daunting, depressing epiphany of just how sleep deprived I have been up until literally my late 30s with how I've lived my life. I mean from age like 14 to 21, I was a competitive swimmer. I was waking up throughout junior high school and high school four forty five every day to go to swim, practice for two hours. Then, I go to school, then I go to swim, practice again for two more hours, do my homework, go to bed, repeat. Chronically sleep deprived through those years, going to college, the same thing. I have memories of just sleepwalking through my life, just so exhausted, not just from the sleep deprivation, but on top of that, like very rigorous training, right? I literally had no energy for anything and then around 21 is when my alcoholism really started to kick in. The next 15 years was a cycle, a progressive cycle, of course, of sleeping, sort of drinking to blackout, passing out, going on three day benders and then experiencing those sleepless nights that occur in the wake of that. It would take three or four days to normalize and terrible nights of laying in bed, sweating and staring at the ceiling and unable to sleep and the shaking and the whole thing. Only to finally get by Wednesday getting one good night's sleep, feeling OK and then repeating and repeating it again, right? I did that for 15 years and it wasn't it. I got sober 31 and then I transferred a lot of my addictive tendencies on onto workaholism so it didn't get that much better. But looking back, it's just unbelievable how much I shortchanged myself from sleep. I think what is the relationship between that early sleep deprivation and my alcoholism? What is the relationship between the alcoholic sleep deprivation and my ability to be a functional human? All I can tell you is that when I look back, I think back on those years, I could barely remember a single book that I read. I couldn't tell you anything that I learned in law school, I barely remember college and my memory overall is not so good. Yeah, it's really like unbelievable when I think about how profound that is and the impact that it's had on out of my life. On top of that, this is separate, I sleepwalked like all the time when I was a kid, and ultimately I grew out of that. But I don't know how that plays into it. But when you hear that, what is your reaction? Dr. Walker: Yeah, so firstly, from the memory point that you mentioned, we know that sleep is critical for learning and memory and in at least three different ways that we can speak about, but what about the long term consequences of that? Well, we have a little bit of data from the situation of airline pilots, right. Who typically have to undergo jetlag that chronically sleep deprived. Firstly, what scientist found when they looked at matching those pilots with sort of someone of similar age, some background, education, lifestyle, et cetera. They found that parts of the brain had actually shrunk. It's what we call atrophy; they lost brain cells. Where they lost brain cells? They'd lost them, particularly in the memory centers of the brain, a structure that we call the hippocampus. The hippocampus which sits on the left and the right side of your brain like a long cigar shape on the left and the right side. It's almost like the informational inbox of your brain. It's very good at receiving new information and memories and holding onto them. That part of the brain had actually deteriorated because of that disrupted sleep schedule. Now, you could argue, well, perhaps it's just something about biased selection that I don't know how it would be with airline pilots, just because of poor memory they don’t go into profession X; piloting is essential with memory. I don't think that's the case but a better demonstration of that was then they looked at how long that they'd been on the job, how many years had they been going through that sort of sleep deficiency. That predicted the magnitude of brain shrinkage, which made me think, OK, I think it's more likely that it has to do with the sleep as well. Is there a potential long term organic atrophy consequence of insufficient sleep on the brain? We seem to think that there is, yes. But again, I think I want to be really careful here and I don't want to be causing people alarm and what I would say is that it is never too late to start sleeping better. That's not just me sort of pulling out the pompoms and trying to be positive. We've got data, in a series of studies and we've done a lot of work and as I mentioned, in an older adults. But if you take a group of midlife adults who are suffering from untreated sleep apnea, heavy snoring, and then you put them on treatment, which is called a C Pap machine - C PAP - the continuous positive airway pressure. By the way, if anyone's listening to this and they think that they suffer from sleep apnea or they have a partner who does, please go and get diagnosed. It is a deathly disease untreated and what they found is that about half of those participants complied to the treatment and about half didn't. They track them over a 10 year period and what they found is that those individuals who complied to the treatment and whose sleep was improved as a consequence, they staved off the onslaught of Alzheimer's disease and cognitive decline by anywhere between 10 to 15 years relative to those who remained untreated or non-compliant with their treatment. In other words, even in midlife. There is evidence to say it's never too late to start sleeping. Rich Roll: Right, but can those brain centers that have atrophy be regenerated or is that a permanent thing? Dr. Walker: We don't know. It depends on what extent of atrophy. We used to think maybe 30 years ago that the brain didn't produce new brain cells once it had matured and once you are an adult. That was your sort of smorgasbord of brain cells and as you lost them through time. Rich Roll: That’s the whole thing, when you drink, you kill brain cells. They never come back. Dr. Walker: They never come back. Yeah, well, that's not true. There are in many regions of the brain that is true. But there are a couple of regions that it's not true. In fact, these memory centers, the hippocampus, that's one of the centers that does actually seem to have some degree of regenerative capacity. How capable of meeting the demand of brain atrophy and damage that system is of regeneration is unclear. What I should note, by the way, is that system of the creation of new brain cells, it's what we call neurogenesis, which I think is a great alternative name for a band rather than just Genesis, Phil. If you deprive a rat of sleep, it fails to have the regulation of that neurogenesis. You lose the capacity for neurogenesis when you are under slept. It becomes this self-fulfilling, negative, vicious cycle of prophecy that if you are not getting sufficient sleep, those brain cells start to deteriorate and atrophy. Then the one thing that could help you get them back is the one thing that you keep depriving yourself of, you lose even the salvation of the sort of the salvaging I should say of that. Rich Roll: Yeah, well, you mentioned pilots traveling from time zone to time zone. On top of that, I want to talk about the medical profession, because here in lay the greatest irony of these people who are dispatched with. Tending to our health has this complete myopic perspective when it comes to prioritizing sleep in their own profession. There's this systemic kind of infrastructure set up that prioritizes lack of sleep, these residents who have to work these 30 hour shifts, this legacy of an old tradition that was set in stone long ago and continues like unbelievably to be the standard operating procedure today, which is not believable. I loved how you told the history of this guy Halsted, right? Who basically was a hard ass back in that at the turn of the century and just said, this is the way we're going to do it. Today we still do it in the manner that he kind of established back then, but it turns out he was like a raging cocaine addict. Dr. Walker: That's right. Yes. William Halsted was the guy who set up the first resident training program in the United States at Johns Hopkins University. It's called a residency for a reason because you're going to become a resident; you're going to live in the hospital. Rich Roll: Right. Dr. Walker: He was known for being able to go these heroic long stretches without needing sleep. People were stunned and he expected his junior residents to match him in that room. Gradually after his death, it emerged the reason why he was able to do that. Halsted in his early career was actually studying the anesthetic properties of cocaine. Unfortunately, he started to use cocaine himself and he became an accidental addict. That was how he was able to just go days straight without seemingly needing sleep. Rich Roll: Apparently set the expectation that everybody else should be able to match to the way that he was. Dr. Walker: To go the same degree now, there were times there were stories where people would say, he would in the operating theater he would have to go and take a break because he was saying he was not feeling well. He was sweating a lot; he seemed to be cold and he would have to go take a break because detoxing during the surgery so he had to go and administer again. There were even stories, he knew that he was an addict and he sought to go into rehab under a different surname. At the time, they were treating cocaine addiction with morphine. Rich Roll: Right. Dr. Walker: Unfortunately, what happened is that he came out of that rehabilitation program with no resolution to his cocaine addiction. But now he had a heroin addiction and the story goes that he would have his shirt, his white shirts sent away to get laundered in places like Paris and they would come back both white and starchy. But there would also be other white related compounds in there. We've never let go of that arcane and I think inane practice, and it's not medical residents who are at fault here. Speak to any of them and none of them will tell you that's what I want to be doing. Rich Roll: Yeah. Dr. Walker: I've had conversations with the dear friend called Peter Attia, who went through the medical practice, is wonderful medical doctor. He describes some shocking history with a lack of sleep. The statistics are just damning. Firstly, what we know is that medical residents who have performed a 30 hour shift will make 400 and 60% more diagnostic errors in the intensive care unit. Secondly, we know that if you're going to have elective surgery, let's say, and your surgeon has slept less than six hours in the previous 24, there are a hundred and seventy percent more likely to cause a major surgical error, such as rupturing a blood vessel or damaging or puncturing an organ. Then, the irony is that a medical resident who's worked a 30 hour shift when they get back in their car to drive home at the end of their shift, they are a hundred and 68% more likely to get into a car crash now returning to the accident and emergency room from which they probably came. But now as a patient rather than a doctor and I've tried with many other people to lobby the medical institute and or institution and try to understand why is this the case? I think some of it has to do with the old boys’ network that it's almost like a hazing, that we went through it, so you have to do it. Man up, suit up, boot up, woman up. You need to get through this. This is a rite of passage and again, it comes back to that idea that thinking that you can fight Mother Nature and evolution is just thick-headed and that's what this is. Rich Roll: I mean I get the idea that you have to develop a level of rigor and emotional resiliency to handle that kind of job. There is something to be said for putting people in challenging situations to see how they function under high stress. But the sleep deprivation aspect of it is just ridiculous. Dr. Walker: You know, when you go through medical school, you take an oath, which is to do no harm, and then you're placed under conditions of insufficient sleep, that statistically will guarantee that you will do more harm than if you were sleeping or working, let's say, just a 16 hour shift. I think some of the pushback that I've received is look, my mind's made up, don't confuse me with the data and you think, okay. Rich Roll: You're the doctor, you're the scientist. You’re the doctors. Dr. Walker: Isn't this self-evident and one of the arguments, though, I think that has some legitimacy is that of continuity of care, that if you are flip flopping back and forth between a resident every six hours, that the continuity of the patient care can decrease. But then I thought about that argument for a long time, and then I looked at the medical systems throughout the world. I asked how long does it take to train their residents and how good is their medical care? What I found is that there are places like New Zealand, France, Switzerland; they all have their residents working no more than 16 hours. Their quality of health care is actually ranks far better in the worldwide statistics than the United States. You can't tell me that you can't train an individual within five years or less at a reasonable amount of sleep and not maintain high quality of medical practice. Rich Roll: Right. Well, part of the problem tracks back to the fact that there's no education on this in medical schools, right? These doctors even become hospital administrators don't have the proper background to make a better decision about this. Dr. Walker: That's exactly right. I myself and some of the researchers, you look at the medical curriculum throughout many of these first world nations, and what you discover is that the average medical resident receives somewhere between an hour and a half to two hours of education on sleep relative to their entire medical program. Now, that strikes me because that's one third of their patients’ lives and that one third of their life spent asleep makes a profound difference than two thirds of waking health life. Why aren't we investing more in the education of sleep for our medical residents? Rich Roll: Well, why aren't we? Have you seen since the book came out and you've been speaking regularly on this, have you seen changes, positive movement in this regard? Dr. Walker: A little, but not too much. Yeah. Unfortunately, I think there are some medical programs around this country at least that are doing better than others. There's a quite a variability, so someone prioritizing it and understanding its importance. But overall, no, I think that same sort of some of that hubris is still present. What do we do to change that? Well I tried early on speaking about this from the statistics of the patients, from point of view of compassion and empathy for our young residents, and that sort of just falls on deaf ears. What I realized is that you have to speak in a currency with which medical institutions and administrators will listen to, which is dollars and cents. When you start to rack up the numbers regarding malpractice suits caused by insufficient sleep they start paying attention. I was just stupid, I thought about appealing in the wrong language. Rich Roll: Guys, you've got to follow the money. Dr. Walker: Yeah, I know. Rich Roll: But this Halsted reminds me of that TV show, “The Knick”, did you watch the show? Now, Steven Soderbergh did a limited series several years ago. I think it was for Showtime, I can't remember but it's about this surgeon played by Clive Owen at the turn of the century is literally nineteen hundred. He's like an opium addict and then he gets introduced to cocaine and heroin. But he's this talented surgeon and he goes into the theater and you see the crazy surgeries that they were doing at the time. It's quite an interesting document. I think you would really like it, but I couldn't help it. And I wonder if this character who's modeled after. Dr. Walker: I suspect so. I suspect if drug abuse, cocaine and such, was involved and he was this extraordinary power and force, that sort of birth into being this new way of medical practice, I well imagine it was based on Halsted. Rich Roll: Right. Well, the relationship between substance and substance abuse and addiction and sleep deprivation is another weigh in this terrain. I mean when you have all these doctors who are being compelled to stay up so late, they're going to find exogenous ways of enhancing their ability to do their jobs. The treatment center that I went to many years ago was known for having lots of doctors and doctors and pilots like the two people that you completely sort of divest yourself of any of all control over to, right?. I just remember being struck at how many surgeons and pilots were in this treatment center, right? There was a brain surgeon who is a morphine addict and there were all kinds of pilots that were addicted to Vicodin. There were anesthesiologists that were fentanyl addicts. You know, they would steal it when they would not use the entire vial and they were using them primarily so that they could function in their in their job capacity. Dr. Walker: That's right. Rich Roll: That’s how it starts. Dr. Walker: That's how I was taught to sort of try to come back from the disruption but what we know is that the risk or the probability of someone abusing drugs, of abuse in the medical profession is significantly higher than the general population. To me, most striking and well and equally striking and equally worrisome statistic recently is that the rates of suicide are far higher in young residents. What we've discovered over the past maybe 10 years and we've been doing a lot of this work, too, is the intimate relationship between sleep and your mental health. What we know is that when you are not getting sufficient sleep, your suicidal thoughts increase, suicidal planning increases, suicide attempts increase. Tragically, suicide completion also increases as well. More generally, what we've discovered and I've been doing this for about 20 years now, we've not been able to discover a single psychiatric condition in which sleep is normal. I think sleep is a profound story to tell and our understanding or treatment, maybe even our prevention of grave mental illness. Rich Roll: Well, certainly in saying that it should be the first stop on the kind of treatment protocol, right? How is your sleep? Let's deal with that first before we look at pharmaceutical interventions. Dr. Walker: Yeah, and we know it's a stabilizing force, both in terms of your psychology, as we mentioned, impulsivity. But also just from a basic reward, brain sensitivity that your addiction potential from a brain perspective is higher with insufficient sleep, same individual, two different sleep conditions, two different addictive profiles. Rich Roll: Right. Wow. Well, I have to reassess my whole life now. Dr. Walker: Oh, I'm so sorry. I know it's terribly bad. Rich Roll: No, it's good. I want to talk about sleep in adolescence and in teens because I think the work that you're doing here and the issues that you're trying to raise awareness around are super important. The implications of chronic sleep deprivation in young people. The relationship to early school hours and how this plays out in terms of academic potential and the mental health implications that you just mentioned. Dr. Walker: Yeah, there's been a remarkable amount of work looking at this issue of early school start times. This incessant model of marching back the school clock hours and the summary of the evidence, really, I think it goes the following: firstly, we see that academic, when you shift schools to a later school start times, when you do a causal intervention, what happens firstly, the academic grades increase, truancy rates decrease, psychological and psychiatric referrals also decrease, but what we also discovered is that the life expectancy of those students increased. You may think, well, hang on a second, how does that work? Well, the leading cause of death in late stage adolescent teens is actually not suicide, it’s road traffic accidents. Here sleep matters enormously. There was one good example. I think it came from Teton County in Wyoming. They shifted their school start times from around 7:30 in the morning to just before nine o'clock in the morning. The only thing more remarkable than the extra hour of sleep that those kids reported getting was the drop in road traffic accidents that following year. After the time switch, there was a 70%, seven zero reduction in car crashes in students, 16 to 18, Rich Roll: Statistically unbelievable. Dr. Walker: It blows my mind, now statistically; you can give a relevance to that. Think of the advent of ABS systems in cars, anti-lock brakes systems that stop your wheels from locking up into hard breaking. That dropped accident rates by around 20% to 25% and it was deemed a revolution. Yet here is a simple biological factor, giving our kids the sleep that they need that will drop accident rates by up to 70%. If our goal as educators truly is to educate and not risk lives in the process, then we are failing our children in a most spectacular manner, with this incessant model of early school start times. When sleep is abundant, minds flourish. When it's not, they don't. Rich Roll: Right. There's so much education I think that needs to be done in this area. As a parent of two teens, I got four kids, two are boys. Any parent knows how difficult it is to wake up a young adolescent in the morning and the frustration that comes with that. But what I've come to better understand by dint of your work is how crucial sleep is for that developing brain, and during Covid, we have one child, our younger child, who's being homeschooled right now. We've let her sleep in as long as she wants, and we don't start her first class until noon. She's getting a ton of sleep. But if you even tried to wake her up at nine o'clock, I mean, forget it. You're going to spend the next hour and a half trying to get this kid up. Clearly, there's a reason why that state of sleep is so deep, right? Like that it is crucial in this developing mind. Dr. Walker: Yeah, and we often have that classic idea of a parent at the weekend pulling the sheets off, the teenager ripping across, you're wasting the day now. But firstly, what we know is that it's not their fault because during that adolescent transition, there is a biological shift in that 24 hour rhythm that they now want to go to bed later and wake up later. Asking a teenager to wake up at seven o'clock in the morning and operate and conduct themselves with good grace and be able to learn effectively is like asking an adult to wake up at three thirty or four in the morning and be the best version of yourself. If I was to wake up at three o'clock in the morning and come through to the kitchen and we’re awake, I'd have to say to my partner, I would say to look darling and she would say, like, why you're so moody. I'm just not the best version of myself, because I've woken up too early and she will definitely tell you that. But I think it's the same misgiving because we don't understand how sleep works with our teenagers. Putting them in the school at that time, seven or eight in the morning, essentially is educating them amnesic. They are at that stage, they are leaky sieves. What will go in will just come out the other side, that’s the first thing that's happening. It's not their fault, it's just their biology. Then, second, at the weekend, they're trying to sleep off a debt that we've lumbered them with during the week because of these early school start times. If you ask parents, if you sort of question parents of teenagers, what proportion of parents think that their teen is getting sufficient sleep and more than 70% of them say, I think my teen is doing fine. I think they're getting the sleep that they need when in reality, less than 15% of those teens are actually getting the sleep that they need. There is a parent to child mismatch in sleep understanding. As a consequence, there is a parent to child transmission of sleep neglect, parents don't see it, they don't understand it, and in 15 or 10, or 20 years’ time, that teenager, lo and behold, seems to have amnesia, and they, with their own kids, will do the same thing. They'll put the sheets up and say, you're wasting a day because it was taught to them by their parents that sleep and getting the right timing of sleep and the right amount of sleep is something shameful. Rich Roll: For that young person, do they need more hours? They do, so in the eight hour rule doesn't really apply. Dr. Walker: No, that's for adults. And in fact, the brain doesn't stop developing until it's about 25 years old. Sleep plays a critical role in what we call brain plasticity, which is modeling the brain. It plays a role early in life. In the first couple of years, sleep seems to actually help wire up the brain. It's almost like sleep at that time of life comes in to a new neighborhood. Like an Internet service provider, it wires all of those homes with high speed fiber optic cables. But then later in life, that's when during the teenage years, we've actually realized which homes are using the high bandwidth and which homes aren't really sort of drawing on that broadband speed. Then, the role of the brain it goes from expanding and creating lots of connections, which is called neurogenesis to then actually synaptic pruning, which is where we now have to make the brain efficient for adulthood. We scoped away the unnecessary and we keep the necessary and sleep performs that role to in later teenage years. As a consequence, if you are chronically under sleeping a teenager, you're effectively stunting brain development, and no one would wish that for their child. Rich Roll: Right, you impede neurogenesis. There are fewer pathways to choose from, and then as you age, basically you have less to choose from, years limiting the brain's capacity to do its job. Dr. Walker: Well, early in life, in the first five or so years, you want to sort of it's almost spray and pray attitude, a little bit like investing. You just gift all regions of the brain, lots of connections. Then, you let experience and time teach the brain which highways and sort of tributaries and avenues and lanes would you like to keep and which should be removed. Now, as you shift later in life, it's all about efficiency. Let's get this brain efficient, because right now, when you've got this too much connectivity, it's good to sort of as a general blueprint to lay down, but then let life tell you which of those networks you should enhance and which you should actually remove and it's later in life that we're removing those. As I said, it's not until we're about twenty five that the brain is finished, all of that maturation, that's why the recommendation is seven to nine hours in adults and I would argue in adults once they're past 25 years old. Before that, you need much more sleep. Rich Roll: Yeah, what would be the ideal amount of sleep for the adolescent or young teen? Dr. Walker: Yeah, it's usually somewhere between eight to 10 hours and going up to maybe 11 hours, depending on that teen. If people want to find out there's a great informational sheet, they can just go to the National Sleep Foundation. It's National Sleep Foundation.org. You can look at the current guidelines that we and other scientists have sort of tried to gather all of the information, say where should we position these windows of sleep duration based on different age ranges? It's a great resource and people are thinking about that for the kids and for their themselves. Rich Roll: If you could bend the ear of the secretary of education, what would be your recommendation in terms of school start time, like 9:00 a.m.? Dr. Walker: I think for teenagers, I would say 10 a.m. 10 at the minimum, and what's interesting is that the younger kids, they can actually wake up early because they haven't gone through that adolescent transition, so they probably could be going to school and learning effectively at, let's say, 9:00 a.m. or even 8:30 a.m. But in those studies, they carefully ask the question, we can't set different times for different age brackets, it's just not practical. I understand why there is resistance in the school system. You can say, why are we starting that early? Some of it has to do a little bit with the bus unions, the bus networks that tried to get kids to school and I get that. I get it's not an easy problem to solve but I also realize that we've put people on the moon and I think we can solve this. Rich Roll: We’ve had tougher problems to solve. Dr. Walker: Yeah, and I'm not trivializing it. It's a big problem and I don't have all of the answers. I'm just a scientist. Rich Roll: Well, there's the kind of mechanistic logistical aspect of solving that problem. But there's also the mental hurdle which comes with education, right? Like getting somebody's head wrapped around the idea of why a 10 a.m. school start is in the best interest of the child is a hurdle. Dr. Walker: For most parents, that's their genetic legacy. Rich Roll: They're, like, I have to get to work, too. Like, what am I supposed to do? Dr. Walker: Right. And that's the hard part so what they did is they looked at say, okay, let's see that we started school at 10 o'clock. That's only going to help the teenagers. But would it hurt the kids who were younger? Because that would then say, well, we can't do this one time fits all phenomenon. What they found is that it didn't hurt the younger kids. They were learning just as effectively. But in the teenagers, they were learning far more effectively. In fact, if you look across the day and you ask, where are those school start times really hurting the teenagers? It's in the first half of the day because they're mostly asleep. You ask any high school teacher, what is my what does my class look like first thing in the morning versus in the afternoon? They’re usually very different as an audience. Rich Roll: What about dealing with things, like, SSRIs and treating ADHD with Adderall and Ritalin, and the overmedication of our young people and the implication on sleep and brain development. Dr. Walker: Yeah, I wrote a little bit about this in the book. It is unfortunate that if you look at ADHD, the current recommended treatment of things like Adderall and Ritalin, and they are some versions of something that looks very much like amphetamine. I'm not dismissing the idea that ADHD exists. I'm not one of those people, it clearly does. I'm not anti-medication by any means. But what I would say is that unfortunately, those medications are very strong wake promoting medications. I mean, if you ask an amphetamine addict if they need sleep when they're using amphetamines, they will laugh at you, right? They'll say, are you kidding me? I can go straight without sleep. Maybe we need to think differently about at least the timing of that medication. Do we want to be medicating kids in the morning or in the evening? Because if those things are wake promoting, we know that kids with ADHD have no normal sleep. They actually have disrupted sleep. We're also starting to find that those medications themselves are sleep disruptors, and so, one wonders what would be the efficacy, the benefit of those medications, which there are, but just timed correctly, and you were at least able to try and protect sleep. But what if we could just come up with better medications that aren't so destructive to sleep? I think that to me would be a better approach. Rich Roll: Is there research on antidepressant medication like the SSRI and the implications for sleep? Dr. Walker: There are. Yeah. So, sleep is usually not normative when you're taking anti-depressants. Now, that's a general statement and it's too general. In fact, it really depends on which type of antidepressant because different antidepressants will shift different neurochemical systems in the brain. SSRI stands for selective serotonin reuptake inhibitor and serotonin is a key neurochemical in the regulation of sleep. We have found historically that people taking antidepressants will typically have a reduction in REM sleep. It really seems to hit hard on REM sleep. As we may come on to discuss sleep and particularly REM sleep provides a form of emotional first aid. REM sleep is what I've described as overnight therapy. There's nothing that I've seen that sort of is that much further from its effect size based on the evidence. One wonders whether or not we can look to alternative medications that, again, have at least some conceptual sensitivity to the things that regulate sleep and try to stay away from disrupting sleep. If sleep offers some form of assistance to depression and we know that insufficient sleep predicts depression. We know that people who are depressed don't sleep very well. They have abnormal sleep patterns. If sleep is a part of that disorder and disordered sleep is a part of depression, then shouldn't we think about the medications that they take that are also sleep disruptive and maybe think about finding ways where we time again the onset of the medication? I don't know how many doctors describe to their patients, not just take two of these, but when; seven o'clock in the morning could be very different than seven o'clock in the evening. In fact, that's true of many medications in terms of their sleep disruptive capacity. Rich Roll: For somebody who, for whatever reason, schedule wise or whatnot, can't seem to carve out the eight hours of sleep a night. Can this be made up for through napping or biphasic or polyphasic sleep like there always seems to be people who are doing all kinds of experiments with polyphasic sleep. But to my mind, I mean obviously more way more than I do. But it seems like those experiments always like somebody’s like I'm just going to sleep every two hours, every four hours, but that never last very long, right? They always end up getting bad. Dr. Walker: It doesn't, the sort of idea of what's called highly polyphasic sleep, some people describe it as the Uberman sort of schedule. Rich Roll: Some people have said this is great optimization. Biohacking, it doesn't work right? Dr. Walker:No, it really doesn't and there is nothing in our biology that would suggest that's how we should be sleeping. In fact, it's quite the opposite. In fact, there's a lot in our biology screaming you should not be sleeping like that. You're not designed to be highly polyphasic in your sleep, meaning multiple bouts of sleep. The only time that we do that is when we're infants. I think Billy Crystal is a long time insomniac. He's got this joke and he says, I sleep like a baby. I'm awake every two hours and that seems to be this highly polyphasic mentality, too. That doesn't seem to be the case. That doesn't seem to be how we should sleep and I would strongly advise people not to do that. Should we be sleeping, though, differently than the way that we are in modernity? I actually think there is an argument for this, because if you look at hunter gatherer tribes whose way of life hasn't changed for thousands of years, they don't sleep the way that we do. They don't sleep in what we call them monophasic pattern, which is trying to get one long single bout at night, and then we're awake for 16 hours. They sleep biphasically, typically depending on what season, winter versus summer. They will sleep for anywhere between sort of six to seven hours at night. Then, they will have the siesta-like behavior in the afternoon where they have a nap getting this sort of fuller opportunity. I think modernity, you could argue has actually dislocated us from how unnatural edict of sleep schedule. Is there any other evidence to support that? There actually is, most people will know this somewhere between about two to four p.m. every day you will have a drop. A pre-programmed and it's genetically hardwired drop in your alertness. It's sort of that you're around the boardroom table after lunch and all of a sudden you start to see these head bobs going on. It's not people listening to good music. They're just giving way to what we call the postprandial dip in alertness. Rich Roll: It is decoupled on some level from the food coma right out of it. Part of it is, I ate a big lunch, but this is independent of that. Dr. Walker: You can prevent people from having lunch and they still have and I put electrodes on the head, we can still measure this alertness drop. It is independent of food. Rich Roll: Right, so siesta. Dr. Walker: Siesta, you can ask, well, if that is how we were designed to sleep, is there any evidence that something goes wrong when you change that natural behavior? That actually happened as a natural well, an unfortunate natural experiment in Greece a couple of decades ago. They decided that they were going to do away with the siesta policy. If you went to Greece in the 1980s and you walked around the towns, you would see on the shop windows, it would say open from 10 to two p.m., close from two to five p.m., and then open from five to 10 p.m. Because there was a standardized siesta practice, they decided to do away with that. Harvard researchers said, OK, we're going to see what happens, what are the consequences. They focused on cardiovascular disease, so they tracked the sleep and the cardiovascular health of well over 23,000 Greeks. What they found is that across that five year period, there was a 37% increased likelihood of having a heart attack, in fact, it was worse in males. In males there was a 60% increase in likelihood of having a heart attack. What was happening, it seemed, if you looked at the data, is that they were still sleeping the same maybe just six hours a night. They would doing away with the nap during the day, and they weren't replacing that sleep time back into their night phase.They were staying true to what they'd been doing before at night, and they'd just been short changed of their sleep during the day and that led to cardiovascular health consequences. Rich Roll: If no siesta, you got to make sure you get the eight hours, but if you're engaging in that Hunter-Gatherer practice, you can go six and two or whatever, and that seems to be fine. Dr. Walker:I would say that there's probably a couple of caveats with naps, though. Naps are a double edged sword if you are struggling with sleep at night. The recommendation is do not nap during the day because what you want to do is build up all of that healthy sleepiness. It's a chemical called adenosine, it's sleep pressure essentially. The longer that you've been awake, the more of that adenosine, the more of that sleep pressure builds up. It's not a mechanical pressure in your brain, don't worry it's a chemical pressure to sleep, then after about 16 hours of being awake, there seems to be enough adenosine, enough sort of sleepiness to be weighing down your shoulders that now you can fall asleep and then stay asleep. If you're someone who has fragile sleep or insomnia, you shouldn't nap during the day because taking a nap during the day; it's almost like a pressure valve on a steam cook up. You just release some of that healthy sleep pressure that's building up. Now, when it comes time to fall asleep or stay asleep at night, it's that much harder. The advice would be, if you don't have sleep problems and you can nap regularly, then I would say naps are just fine. But if you can't do it regularly, and especially if you suffer from sleep problems, try to stay away from naps. If you are going to nap, nap before 2:00 p.m. in the afternoon, going later than that can be problematic for your sleep. It's a little bit like snacking before your main meal. It just takes the edge off your appetite. It's the same way with naps. Rich Roll: I'm sure you or somebody has studied what happens if you take exogenous adenosine, right? Like, wouldn't that seem to be the way in to resolving this problem for people that have insomnia? Dr. Walker: How to get it across the blood brain barrier, which is a protective layer on the brain? There are some issues around toxicity, as well. Yeah, that certainly would have been the idea. But what's lovely is that you can increase sort of sleep pressure in a number of non-pharmacological ways and exercise is a great demonstration of that. I think we can speak about all of these different over-the-counter medications that people try to invest in and think that that's going to give them a good night of sleep. But there are probably two really simple things that you can do. Non medication that are, if you look at the data, are almost guaranteed to improve your sleep, which is some form of physical activity most days or at least several days a week. The second is deal with your anxiety. Anxiety is the principal cause of insomnia. It's not the only cause, but it's the current working model of insomnia that people who have a high fight or flight activation of the nervous system. They also have high levels of stress chemicals such as cortisol, and that seems to be very predictive of their insomnia, if you can start to manage your anxiety, for example, meditation is a fantastic practice. Before I was writing the book and I was sort of starting to research, I was a bit of a stupid, hard-nosed scientist. I just thought this meditation stuff was maybe a little bit woo woo and sort of kumbaya, and we all hold hands. I started to look at the data, a data was immensely powerful and very robust that people, when they are suffering from insomnia, if you put them into a meditation and mindful practice, you can actually drop the severity of the insomnia in a way that medications even prescription medications, can't come close to. Rich Roll: Yeah, I just know well first of all, if I don't exercise, forget about it. I know I'm going to struggle with sleep at night. If and when I have difficulty falling asleep or I wake up in the middle of the night, I've become very attuned to what my mind is doing. It will generally default to some problem that I'm having or conflict that I'm trying to resolve and I'll just loop some narrative. That produces a tremendous amount of anxiety, which obviously prevents me from falling asleep. I notice that and then I course correct through either some kind of mindfulness practice to kind of create space and push that narrative aside or overcome it with a different narrative. Sometimes, I'll just think about a book that I'm reading or a movie that I saw, and I'll just immerse myself in that narrative and and that's like a distraction. Dr. Walker: Exactly. Rich Roll: Literally short circuits, that other anxiety producing narrative and I fall asleep. Dr. Walker: You're so right. I think in this modern day and age; MTV, fast food, 24/7 society, we're constantly on sort of reception, particularly with now all of this digital technology. Rarely do we do reflection and unfortunately, the one time when we do reflection is one that head hits the pillow. That's the last time that you want to go into rumination. You don't want the Rolodex of anxiety spinning up, which is what you are describing, because that leads to something that we call catastrophizing, that you start thinking, oh, what didn't I do today and what do I need to do more of tomorrow, then I forgot this. At that point good sleep is not going to be invited into the brain. By the way, counting sheep does not work and there was a scientific study done by a colleague of mine at UC Berkeley that demonstrated, in fact, if anything, it hurts your sleep. Rich Roll: But if you’re catastrophizing, it would probably be better to start counting sheep? Dr. Walker: It could be, but what you described was actually what she found, far better was to engage in some kind of a mental aspect and what they found was take yourself on a walk. Think about a walk in the forest or in nature or down on the beach and just start to try to walk yourself through that, or think about a book that you're reading or think about sort of a podcast and anything to get the mind off itself. For example, I feel embarrassed to say this, but I love racing cars. If I'm struggling with sleep, which I am, I do to, I am not immune to bad nights of sleep and I have bad bouts of insomnia. Rich Roll: So comforting to hear that. Dr. Walker: I'm just as fragile and what I do is, I'll put myself and I'll think about the track and I'll drive myself around the track. I know when I need to which gear I need to be in, where my braking zones are. Then the next thing I know is I'm waking up in the morning, and just drifted off, because I’ve taken my mind off. Rich Roll: Yeah, that’s great. It’s sort of the different version of what I do. What kinds of car you race? Dr. Walker: Oh gosh, I've raced all sorts of BMW Porsches, but my real love and the car that I own is a little Mazda Miata. When you're a professor, you can't really go racing in half million dollar cars. I love it to pieces. It is a car unlike Ferrari or Porsche. When you're going 40 miles an hour, it feels like you're doing 100. Whereas in a Porsche, when you're doing 100, it feels like 40 miles an hour. I'm usually the slowest guy on track, but it brings me a lot of joy and satisfaction. Rich Roll: That's cool. Well, let's talk a little bit about best practices that I feel like we're at that juncture. I want to do this by walking you through the extreme lengths that I go. Dr. Walker:I know a little idiosyncrasy, so tend to include it. Rich Roll: Yeah, I sleep on a tent, causes a lot of consternation and confusion from people that listen to this show. But I'll just provide a little background to that, like historically I’ve had issues falling asleep. Part of it, and I'm interested in your take on this is I think my sense is that it's germinates somewhat from being like an extreme ultra endurance athlete, I've gone through periods of my life where I've put my body through just unbelievable rigor, like twenty five hour training weeks where you're just so exhausted. Sleep is a non-issue. Sleep is not a problem when you're pushing yourself that hard. But it's been many years since I've been kind of having that space now but I've acclimated, my physical body is acclimated to doing that, right. Now, if I go out for a one hour run or I go on a casual bike ride, it's not enough. Like I'm not getting enough of the fatigue to create the restful state that I aspire to be. Like I have to exercise more than the average person, which is challenging when you're a busy person. There's that, on top of that, my body's like a furnace, like I literally burn hot and my wife likes the bedroom a lot warmer than that I do. We would have these this back and forth over many years where it's too cold for her to I'm on top of all the cover. She's underneath them, shivering; it wasn't working. As kind of a joke, I went, we have a flat roof off of our bedroom. I went and I just pulled a twin mattress up there and slept there one night, had an unbelievable night of sleep. I thought, this is fantastic. It's nice and cold out the desert area even in the summer.That I graduated from that into getting a tent and I've been sleeping in a tent ever since. I absolutely love it. The cold air being under the stars and being under a bunch of blankets, including a gravity blanket, which I'd love your thoughts on, which I found to be really helpful. Speaking about the sympathetic nervous system, trying to calm myself down. I'm asking nature sounds and magnesium like all kinds of stuff and the idea being to create the optimal situation for the best opportunity for eight hours of sleep every night. Like yourself, I don't always, despite all of that sleep, still eludes me many nights. But I'm but more often than not, I'm getting more high quality sleep than I used to. But I'm interested in how this kind of measures up with what you found through your studies about best practices, specifically temperature, air quality, all these kinds of things. Dr. Walker: Yeah, I think there are probably maybe five tips for better sleep tonight. If you sort of suggest that start trying to optimize your sleep and temperature, regularity, darkness, walk it out and then alcohol and caffeine. I say to the last one, because usually if you don't find me deeply unappealing right now, you will after that fifth one temperature is a fascinating one. We know that your brain and your body need to drop their core temperature by about one degree Celsius or about two to three degrees Fahrenheit for you to fall asleep and then stay asleep across the night. That's the reason that you'll always find it easier to fall asleep in a room that's too cold than too hot, because too cold is taking you in the right thermal direction for good sleep. That's why sleeping in a tent, now we understand we're in Southern California, but nevertheless, it gets cooler at night than it is during the day. Rich Roll: Yeah, I wouldn't be doing this in Boston. Yeah, I mean, typically it's low 40s and it goes down into the high 30s. I've never not slept in the tent because it was too cold. I know that in your research you found there is an inflection point at which point perhaps too cold is not so good. Dr. Walker: Yeah. Once you get into an extreme. Rich Roll: But I have to tell you when it's thirty eight degrees, I'm happy. Yeah. I sleep pretty dang well. I got a lot of blankets on. Dr. Walker: Yeah and it's sort of the local temperature. Rich Roll: Here's the other thing, I always have my feet sticking out. I do not have my feet under the covers yet. Dr. Walker: You know why? Rich Roll: Yeah, I think I know why. Dr. Walker: It’s because your hands and your feet that are these incredible radiators of heat. Your hands and your feet are highly vascular. In other words, there is this crisscross of vessels very close to the surface and it's very rich in its vascular nature, both your hands and your feet. At night, what the body wants to do is almost like a snake charmer, draw the heat out of the core of the body and evacuated through the extremities. The extremities in this case, for us, human beings are hands and feet as well as head. That's why you will sometimes see rebellious when you see kids and you kind of tuck them in all nicely. You look at your wife and you smile and it's all beautiful, then you go back in two hours later, just before you go to bed and these rebellious legs dangling out, sticking out. It's because you're trying to evacuate the heat. You're wise in doing that because they are wonderful thermal discharges, so that's temperature. We do need to drop that temperature. It's different for different people, but I think the recommendation would probably be about sixty five degrees or so for most people. Now, that's obviously averaging across men and women and it's different there too, as you mentioned, which is around about if I do my math correctly, it's probably around about eighteen point three degrees celsius. That's temperature and that's why I think you definitely will start to sleep better than you at least would do otherwise on a constant temperature. Because there's another way that modernity is dislocated as from a natural edict of sleep, which is we set a thermostat of maybe seventy or seventy two degrees throughout the day in the night, and that's not how we were sleeping. Now, if you go back to those hunter gatherers, by the way, for whom you are in some ways mimicking their sleeping existence, they don't go to bed really on the basis of light, which is what we thought. They usually will go to bed about an hour and a half to two hours after sundown. Then when they wake up and they don't have alarms, if you ask them about this idea of artificially terminating sleep with an alarm, they’re perplexed. Also, rates of insomnia in the general first world population is somewhere between 10% to 15%. In those Hunter-Gatherer tribes, it's less than 5%. Rich Roll: Also, they’re moving all day long. Dr. Walker: They're moving all day long. We can look at diet as well, but, so what is determining their sleep onset and their sleep offset is not light, it's temperature. When that and if you ask people if you just bring them into the laboratory and you say at what point do you feel sleepy at night? It's at the point where their core body temperature is on the steepest decline. Now, they don't know that even though, unfortunately, we've placed a rectal probe inside of them, which is no fun for either the experimenter to insert or the participant to receive, but they are on the awesome downslope of their thermal evacuation and that's when they feel sleepy. When the Hunter-Gatherer tribes wish to wake up is before dawn, just before dawn, but it's as the temperature starts to rise back up. It turns out that we actually need to warm up a little bit to get cold. We need to bring the blood to the surface of the skin. That's why cold must be in the bedroom. But you can wear socks if you want or you can have a hot water bottle. But keep it cold because warming the feet or sticking them out of the mattress will help your body evacuate the heat and plummet your core body temperature. It's the reason, by the way, that hot baths and showers work for good sleep as well. Rich Roll: In a counterintuitive way, right? Because you think you're warming up. I mean, you're nice and toasty. Your vessels are dilating. Dr. Walker: When you get out the bath, you got rosy cheeks. All of the blood comes to the surface. And when you get out of the bath, your core body temperature is dropping precipitously. That's why you fall asleep. It's called the Warm Bath Effect in sleep science, it's so reliable. Then when they're starting to wake up is when they're starting to warm up. We need to sort of warm up to get cold, to get to sleep. We need to stay cold, to stay asleep. Then we need to warm up to wake up. That's the sort of temperature transition, so that's temperature. The next is regularity. Go to bed at the same time and wake up at the same time. No matter whether it's the weekday or the weekend or even if you've had a bad night of sleep, don't change it. Resist the urge. My recommendation to people who've had a bad night of insomnia, they'll say, should I get to bed earlier? Should I wake up later? Do nothing, don't go to bed any earlier. Don't try to wake up any later. Keep to your schedule. By the way, I'm giving these tips or these rules. People don't respond to rules. People respond to reasons, not rules. Rich Roll: You’re the diplomat. Dr. Walker: Trying to give some explanation as to underlying it. But the reason that regularity is king is because it will anchor your sleep and it will improve the quantity and the quality of that sleep, because deep within your brain, there is a master 24 hour clock and it expects regularity and thrives best under conditions of regularity, including the regulation of your sleep-wake schedule. Rich Roll: I'm sorry, I just want to interrupt with one thing which is on that subject of the internal clock. Does it matter in the context of getting eight hours if you choose to go to bed at nine o'clock or you go to bed at 11 o'clock if you're getting eight hours? Is that going to impact the quality of your sleep? Like, I know personally, like I need to go to bed early. If I still get eight hours, but I go to bed late, it's not the same thing. Dr. Walker: Yeah, we mentioned that overall for the average adult you get most of your deep sleep in the first half of the night, most of your sleep in the second half of the night. But it's not quite that simple. By the way some people will say to me, isn't the sleep that you get before midnight twice as valuable as that you get after midnight? There's nothing about the sleep that you were getting at eleven fifty nine p.m. and the sleep that you're getting at 12:01 AM and that's a fallacy. But what you described is important and it's a nuance.It comes back to what we call Chronotype. Are you a morning type, evening type or somewhere in between? It's about a third split across the population. You don't get to decide. It's not if you're a night owl, it's not your fault. It's gifted by way largely of your genetics. It was gifted to you at birth and it is hardwired. We now know the genes, at least six different genes determine whether you're a morning log or an evening owl or sitting somewhere in between. Rich Roll: But it's interesting to know that that's a genetic disposition. You can't compel a night owl to be a morning person. Dr. Walker: People have done all sorts of incredible things and there is some degree of wiggle room you can do. I think there's about five or six different things that they tried, but all you can really do is drag a night owl back by maybe thirty minutes and that's really it. What you're describing there in terms of the quality of your sleep is important because it's less about where any adult places that eight hours on the 24 hour clock face, it's more about where that individual adult is trying to sleep in harmony with their Chronotype rather than against their Chronotype. Now, unfortunately, modernity is predisposed to a heavy bias and discrimination towards morning types. It's the type of culture that rise and grind you get up in the morning and it's all about the early bird catches the worm. Well, I can also tell you that, the second mouse gets the cheese, so you need to be really mindful of your Chronotype. You can figure out your Chronotype type if you want, you can just go online and you can probably search something called morningness or eveningness, questionnaire. I can send you a link that we can even put in the show, notes the M.E.Q. It's a series of questions and you will determine what type you are trying to then sleep at the right timing in accordance, in harmony, rather than in the synchrony of your Chronotype is when you will get the best quality of sleep. That's why you say if I go to bed at midnight and I sleep in it till 8:00, sometimes I kind of have a sleep hangover. I just feel miserable. But if I get to bed at whatever time you normally do earlier in the evening and wake up earlier, that's my sweet spot. Rich Roll: Right. Most people probably know what their type though, right? Dr. Walker: They do. Well, I think yes and no, because in some ways even the middle ground folks will think that they are perhaps more evening type than they actually are because of technology. Now, we've done a lot of work in the sleep field. By the way, in this podcast, when I've said we did something, I mean that sort of, or when I say, I did something I my community, and when I say we did something, I mean they did something. But we've done a lot of work looking at technology and the invasion of technology into our lives and into our evenings and into the bedroom. Certainly, those blue light devices are damaging to the release of melatonin, which will come on to when we speak about darkness. But it's not really that which now seems to be carrying the vote of technology-based sleep disruption. It's that these things are activating. They are designed to capture your attention and make you more alert. In fact, it's what ends up happening is that you have sleep procrastination where you're using these devices, you're working on your laptop and you think I'm not sleepy. I don't feel tired. But if there were to be some electromagnetic pulse that wiped out all of technology what you would realize is that at 10:30, all the lights went out, you couldn't do anything. Within five or ten minutes, you think, gosh, actually, you know what? I really am sleepy and technology will mask your sleepiness. That activating nature of technology hits the mute button on your sleepiness so you don't perceive it. Rich Roll: Right, in a multifaceted way. There's the dopamine induction of social media scrolling, but there's also the light spectrum and all of that, right? Dr. Walker: That's right. Rich Roll: Impacting your body's ability to properly self-regulate. Dr. Walker: Yeah, if you really have to take your phone into your bedroom, I don't personally. But again, that's just me. I would say the one rule I would offer to you is that if you're going to be using your phone in the bedroom, you have to be standing up. At that point, after about five or six minutes, you're like, you know what? I just want to if you sit down on the bed, I'm sorry, my phone goes away. Rich Roll: Here's what's depressing, though. You talk about this like how long before you need to go to bed? Should you shut the screen off? It was like a number of hours, right? Like if you watch a movie and then go to bed, that movie should be concluded. Like, I don't know, what did you say? Like two hours or something like that? Dr. Walker: Well, it really depends on watching television or a movie. As long as it's not inside of the bedroom, we really shouldn't be watching television inside of the bedroom, because you want to associate your bed with simply the place of being asleep or for intimacy. That's really what we recommend the bed for. Don't be working on there. Don't be eating on your bed. Don't be watching television on your bed consuming Netflix. I think it's really about computers and iPads and cell phones or laptops, tablets. I think watching television outside of the bedroom is okay. One of the dangers, however, when I ask people, if they say I'm having sleep problems, I'll say, do you nap during the day and they'll say, no, I never nap. Then I say, well, but when you're watching television on the couch in the evening, do you sometimes fall asleep watching television? They say, yeah, I do that all the time. That's an accidental nap and it's the worst time to nap, too, because, again, it's right before your main meal of sleep. I would say that if you're doing something that helps you wind down and just disengage from the day, disengage from those stresses, that's fine, be it reading a book, watching a mindless movie. But in the last hour before bed, stay away from anything that is cognitively and especially emotionally activating. Don't be checking emails. Don't be sending texts, don't be engaging in movies that are action, horror movies that have you wired. Try to stay away from those things. Rich Roll: Yeah, so let's talk about caffeine and alcohol, right? Disappointingly, caffeine has like an eight hour half-life, right? If you have a cup of coffee in the morning you’re still contending with it when you go to bed. Dr. Walker:It's tough, yeah, alcohol and caffeine. Everyone knows that caffeine is an alerting substance. It's in a class of drugs that we call the psychoactive stimulants. Interesting, it's one of the only psychoactive stimulants that we readily give to children without too much concern. Many people know that's how caffeine works. But people may not realize that caffeine can have two additional damaging effects on your sleep. The first comes down to, as you said, the duration of action that caffeine has for most people, a half-life of what we call about five to six hours. In other words, after about five to six hours, 50% of that caffeine is still in your system, which means that caffeine has a quarter life of between ten to twelve hours. If you have a cup of coffee at, say, 2:00 pm, a quarter of that caffeine could still be circulating your brain at midnight. It would be the equivalent of a 2 p.m. cup of coffee is the equivalent of getting into bed and just before you turn out the light, you speak a quarter of a cup of Starbucks and you hope for a good night of sleep, it's probably not going to happen. There are differences from one individual to the next. It comes down to the specific enzyme that degrades caffeine. Some people have a genetic variant, what we call a polymorphism that has a faster metabolic rate for the degradation of caffeine. Other people have slow that usually determines I'm a sensitive person, I'm not sensitive. But even if you're one of those people and some people say this to me, look, I can have an espresso with dinner, I fall asleep fine and I stay asleep, so no problem. That's not quite true, because even if you fall asleep and stay asleep, caffeine can actually decrease the amount of deep non REM sleep that you get. It can decrease the quality of that deep sleep by up to 20%. Now, for me to drop your deep sleep quality, I would have to age you by a decade. Or you could do it with a cup of coffee in the evening each and every night, and the problem is that then those people, when they wake up the next morning, they don't remember struggling to fall asleep. They don't remember waking up frequently throughout the night. They don't put two and two together. But now they feel unrefreshed and unrestored by their sleep because they weren't getting the deep sleep. Now, they find themselves reaching out for more coffee, three cups of coffee in the morning. Then because they may not be able to get to sleep at night, then they're reaching for sleeping pills. It's the stimulant in the morning. It's a sedative in the evening, and it's a very difficult cycle to break, so that's caffeine. Alcohol is probably the most misunderstood sleep aid that there is out there. It's anything but a sleep aid. You've mentioned how your sleep is so disrupted. First, the alcohol is in a class of drugs that we call the sedatives, and sedation is not sleep. But when we have a couple of drinks in the evening and we say, gosh, I just fell asleep like that, you're mistaking sedation for sleep. If I were to show you your electrical patterns of brainwave activity with and without alcohol, they're not the same. It's not naturalistic brainwave activity. The second problem with alcohol is that it fragments your sleep so that you wake up many more times throughout the night. Not only is your sleep going to be poor, quality is will come onto it's also just not going to be consolidated. It’s not that nice, long duration of uninterrupted sleep. Rich Roll: Because as your body is processing the alcohol, the depressant aspect of that drug is wearing off and there's sort of rubber banding actually you wake up at 2:00 or 3:00 in the morning. Dr. Walker: Yeah. It actually will start just as you mentioned, it will trigger activation of the fight or flight branch. You start to come back online in terms of that stress related branch of the nervous system. Also, stress related neurochemicals, we know, are starting to get increased as the the alcohol is metabolized. That's what causes the fragmentation of your sleep. The final problem with alcohol is that it's a very potent suppressor of your REM sleep, of your dream sleep, which we've mentioned before in terms of all of its benefits. I think that's the reason that alcohol should just be strongly advised against the nightcap by medical practitioners. But I would just say two things. Firstly, with tongue in cheek you could look at that data and say, well, then I should just go to the pub in the morning and that way the alcohol is out of my system in the evening and now. Rich Roll: Now we’re talking, the problem with me is if I go to the pub in the morning, I'm at the pub at night, too. Dr. Walker: I would never say that as a health care professional. Rich Roll: But what about like just a glass? Like I'm having a glass of wine at dinner? Dr. Walker:Yeah, I would love to say that based on the data, that doesn't have an impact. But if you look at the data, even the glass can have a measurable impact. But look, the other thing I want to note is this and I think it's something that I've learned in after the book was published. I'm embarrassed in the way I was acting before. I don't want to be puritanical here, Rich. I don't want to tell people how to live their lives. I'm just a scientist. All I want to try and do, and I may be too enthusiastic in doing this is gift people with the science and the knowledge of sleep, and then they can make an empowered choice as to how they want to live their life if they're trying to optimize their sleep. I do want to mention that I'm not finger wagging and I shouldn't be telling anyone that. Rich Roll: Nah, I don't think anyone's getting that impression. I think it's like, look, this is what's going on. Make your own, choose accordingly. Right. But just so everybody knows, let's be clear about what the science says in terms of how this impacts you. Dr. Walker: Yeah, but I think I've been sometimes overstepped. Rich Roll: You’re such a gentle guy, but I also should say, because you talk about this stuff a lot, but you're so enthusiastic your whole body like lights up. Dr. Walker: Oh, gosh. It's the most I fell in love with. I fell asleep like a blind, it was just the most amazing thing as I was starting to study it. It is a love affair that has lasted me 20 years and I am still beguiled by this beautiful thing called sleep at night. Rich Roll: Yeah. There's so much more still to be learned, right. Dr. Walker: I mean, it remains one of the last great scientific mysteries. I would say, though, and the reason that someone like me is able to write a book that's over a hundred thirty thousand words is because we've learned more in the previous 50 years about sleep than we did in the previous 5000. Even just 30 or 40 years ago, we used to ask the question what is sleep good for? The crass answer was that, well, we sleep to cure sleepiness, which is the fatuous equivalent of saying we eat to cure hunger. That tells you nothing about the nutritional, physiological, metabolic benefits of food. Now, 30 or 40 years later, we've had to upend that question. We've had to ask, is there any major organ system in your body or is there any operation of the mind that isn't wonderfully enhanced when we get sleep or demonstrably impaired when we don't get enough. The answer seems to be no, right? Rich Roll: I have to ask you this. Every full moon, I don't sleep and I don't know if it's psychosomatic or there's some kind of lunar gravitational pull occurring. But have you looked at this? Dr. Walker: We have. Rich Roll: Have you? Dr. Walker:Yeah. Rich Roll: Please do tell. Dr. Walker: There's some conflicting evidence. Some reports have found this effect, other reports have not. It may be different for men and women. Even some of the reports are saying on average, people sleep less with the full moon. If you have a thought about what the term means, lunatic. It occurred to me when I was doing that work based on the relationship between sleep and your emotional health, that you essentially your emotional integrity falls apart when you're not getting sufficient sleep.You become emotionally unhinged. You become pendulum like in your emotional irrationality. It occurred to me I wonder if part of the derivative of that term, we've got all of these things,the werewolf and people getting crazy. Rich Roll: Right. Yeah. Like when the moon's out, people lose their minds. Dr. Walker: Right. I think some of that is due to different practices around the celebration of the moon phases, et cetera. But I think if you believe some of the reports but again, some of the reports have failed to find this effect, sleep duration decreases. Why would that be? There are some theories around that, which actually I should finish up my tips and there's just two more of them.This is nice because it brings us back to this with a full moon. Obviously, as long as it's not a cloudy night, you get more luminance, right. That light of that luminance can actually decrease the hormone of melatonin. This comes back to what I think the the fourth out of the five tips, which is darkness. We are a dark-deprived society in this modern era, and we need darkness at night to trigger the release of this hormone called melatonin. Melatonin is often called the vampire hormone, not because it makes you want to look longingly at people's necklines and, bite in. It's because it comes out at night. It's the hormone of darkness. Melatonin helps time the healthy onset of sleep and so, the recommendation would be in the last hour before bed. Don't just stay away from those blue light emitting devices. Try dimming down half of the lights in your house. You would actually be surprised at how sleepy and soporific that change can be. That's why I love the idea of sleeping in a tent, because all of a sudden you are removed from all of that, polluting electric light even at night. Now, we should reverse engineer that trick during the day. In the first half of the day, it's critical to get some exposure to daylight. You can go outside, but it doesn't mean that you have to go outside just being next to a window, try to get at least 40 minutes of direct sunlight each and every morning. That will really help because that will then stamp the breaks on melatonin. It will shut it down and you will feel more alert. The more alert you feel, the more healthy sleepiness, the more of that adenosine, which is the sleep pressure chemical that you will build up and then the better your sleep will be at night. Rich Roll: Right. Dr. Walker: That's sort of darkness end and I think that's perhaps part of the explanation why the full moon can maybe disrupt sleep because it's nowhere near like sunlight, but it's still a light invasion. Rich Roll: I wear the eye mask and the whole thing. Oh, I think there's something more mysterious at play. I don't know. But maybe I'll try taking melatonin. I know that you've said taking melatonin as a matter of course, is not a good idea. It's really for when you're traveling across time zones. Yeah, but maybe I'll try it when the next full moon cycle. Dr. Walker: Yeah, you can try it. I mean, melatonin, as I mentioned, it regulates the timing of your sleep, but it doesn't actually really help in the generation of sleep. If you look at people who are not jet lagged and who are under the age of 50, melatonin and all of the placebo controlled studies that we found doesn't really change the quantity or the quality of your sleep. Melatonin, you can think of it a little bit like the starting official at the hundred meter race. Melatonin is the thing that will gather all of the the racers to the start and then begin the great sleep race. But melatonin doesn't participate in the race itself. That's a whole different set of brain chemicals. But I would say two things regarding melatonin. First, if you think that it's working for you. Then the placebo effect is the most reliable effect in all of pharmacology, with the exception of probably an adrenaline injection to your heart. No harm, no foul there. The caveat that I would like to add to that secondarily is it's over the counter, at least here in the United States, which means it's not regulated by the FDA. In a study that looked at over 20 different brands of melatonin, what they found is that based on what it said on the bottle relative to what was actually in those melatonin pills, it was anywhere between 80% less, or up to 460% more than what it said on the bottle. It's a wild west, you don't really know. Rich Roll: Is there a trusted brand? Dr. Walker: Well, I think firstly, I should also mention that melatonin is still largely a safe compound even in high doses.Its concern from that aspect is perhaps lower but because it's unregulated, one of the things I've been seeing right now are melatonin gummies for kids. Maybe we'll learn more about melatonin and it could help kids with sleep problems or sleep disorders. But if it's unregulated, you don't know what you’re giving them. Rich Roll: One of the concerns would be, if you’re taking it all the time, doesn't that signal your body to stop producing it? Dr. Walker: That's right. That's the major sort of issue, is that most people are taking too much melatonin. The taking usually between five milligrams, up to 10 milligrams. I would recommend, based on the science, somewhere between just point five to three milligrams, because if you're dosing any higher, your body has this beautiful network of feedback loops and it starts to think, well, my goodness, I don't need to produce melatonin because I'm getting it every night in very high dose. I can just shut down my own melatonin production. That's the danger, just be a little bit mindful on that. Rich Roll: On the subject of light talking about the light on a full moon. I've come to develop a greater appreciation for the brain's capacity to process spectrum of light and how that relates to how we calibrate our internal clock like I had neuroscientist Andrew Huberman here, you know? Dr. Walker: Oh, yes, from Stanford actually we've never met. But we know of each other. At some point we should get together and mind meld because I think we'd have a lovely time together. Rich Roll: Yeah. He's doing some interesting work, but he talks a lot about how really eyes is the brain. Like the optic nerve is part of the brain and the sensitivity of the optic nerve to all these variations and light spectrum. He talks about at how looking at a sunset kind of helps calibrate all of that, all of these different things. I was thinking about that the other day because I play this game when I wake up with myself, when I wake up in the morning, I open up my eyes. I don't have an alarm clock and I try to guess exactly what time it is. It's pretty amazing, like I'm generally I don't always get it right, but I'm generally like within two minutes of the precise time. I thought, is that because my eye knows the specific light spectrum of what time of day it is, or is it my internal clock, like what is that? But there is this deep knowing, I think that we have, when we are more in nature where we're attuned to these rhythms. Dr. Walker: I think it's a combination of both. By the way, his work is just fantastic. I know you've had him on your show he is just a brilliant scientist; to be so eloquent and beautiful. Rich Roll: He's very effective communicator. He knows how to explain things in a way where people can really understand what he's talking about. Dr. Walker: Yeah, he's wonderful. But I think it's a combination of those two things. I think many of us, even if we've got blackout curtains and sort of we're wearing an eye mask, we will wake up. I think we have some general sense, but maybe plus or minus an hour in terms of accuracy that, okay, it's still probably the middle of the night or it kind of feels like late in the morning. In part, that's because you do have an internal 24 hour clock. But I also think that there's something that we've lost in terms of our light exposure that you have gained back, which is that it's not just that your internal clock, which may get you within one hour plus or minus, it's not bad at doing that. But when you open up your eyes and you get additional exogenous information, which is from the outside world, rather than the endogenous clock time that your 24 hour clock is giving you, then you shift from plus or minus an hour of accuracy to maybe plus or minus five minutes. Rich Roll: Yeah, it’s fascinating. Dr. Walker:I love this. When I retire, maybe I'll look at this because there's something very strange about sleep and time that is utterly paradoxical. What I mean by this is you can say, OK, I've got to wake up cause I'm going to meet Matt Walker in Berkeley. We're going to grab coffee and I've got to get this early morning flight from LAX. You set your alarm for five o'clock in the morning and guaranteed you will wake up at four fifty eight in the morning. Rich Roll: Right, 100%. How is that possible? Dr. Walker: It happens too frequently for it to be just by chance. Somewhere, your brain has this quartz like precision of clock counting. However, there is an absence of time, particularly in training, because all of us have probably had that experience that our alarm goes off. We were in this strange dream and then we hit the snooze button and our snooze button is just two minutes. We go right back into the dream again and then the snooze button goes off. You think, hang on a second, that felt like almost an hour of an experience. There is this temporal mismatch where, when we go into the dream state, we can almost fold and compress time like a concertina. Rich Roll: It's like Inception. Dr. Walker: Yeah, and I think it's no big surprise that Nolan picked up on that with the help of maybe some sleep specialists offering that advice. We know that you get this dilation, I've called it's a dream dilation or dream time dilation works all the time. Rich Roll: Right. What do you make of that? Like what would be the evolutionary advantage of that? Dr. Walker: Well, it may be that there is no necessarily evolutionary advantage, but there may be a brain mechanism that explains it, because what we know is that memories are replayed during both deep sleep and REM sleep. Now, when we are in deep sleep, memories are actually sped up. The brain will actually be replaying those memories anywhere between five to 20 times faster. But when we go into dream sleep, the replay is actually much slower. That’s may be why, if you want to speak about it, that's usually the one question I look forward to least when I give talks, someone put their hand up and say, is inception possible, and my heart just sinks. I start seeing a spinning top of the music that comes by. But I think that's why Nolan had that beautiful idea that when you descend down into these different levels of sleep, a minute of time in the real world could be five minutes of time in the dream world. Then if he gets you to a deeper dream state then a minute of time in the real world is two hours or two days or 50 years. Rich Roll: Well, with the premise being I'm going to anchor this memory or this concept or this idea in this human's brain. How do you do that in an effective way where it's going to stay, right? When you think about this in the context of morphing time constructs, if you have a dream state in which memories are accelerated, that's certainly going to aid in the development of skill acquisition, right? Like you're repeating a memory or a behavior or just imagine, you're in jujitsu and you learn a new maneuver or whatever, and you're replaying that in your mind. Of course, that's going to anchor that. Then the slowing down is almost like a visualization. Well, both of those things would work in tandem to really sort of calcify neural pathways around like a new concept. Dr. Walker: You need to be a scientist. Director of my sleep sensor? Rich Roll: My mom would be very happy if I’m in the medical school. Dr. Walker: No, you're too precious in what you do otherwise. But you're absolutely right that I think what we know is that deep sleep well, one of its functions is that it will hit the save button on your memories so that you don't forget. Deep sleep will future proof that information within the brain and in part it's just as you said, it's deep sleep that's basically scoring the memory trace, almost etching it into the glass of the brain, but then you dream sleep comes along and what we've realized is that dreams sleep does something very different from memories. Sleep is much more intelligent than we ever gave it credit. When it comes to information processing, sleep not only strengthens individual memories, it will intelligently stitch and associate those new memories together. It seems to be during sleep, particularly during dream sleep when we perform, it's almost like informational alchemy or it's like group therapy for memories. Maybe that's a better analogy, that sleep gathers in all of this information that you've been learning during the day and everyone gets a name badge, but sleep forces you to go and speak to the people not at the front of the room that you think I've got the most obvious connection with. It forces you to speak to the people at the back of the room that you think you've got no connection with at all. Now, it turns out that you do, and it's a non obvious connection, but it's a potentially powerful one nonetheless, because when you start to fuse things together that shouldn't normally go together, but often marked advances in evolutionary fitness, it sounds like the biological basis of creativity. That's where we see dream sleep providing a benefit. You wake up the next day with a revised mind wide web of associations and you are capable of divining solutions to previously impenetrable problems. It's the reason that you've never been told to stay awake on a problem. Rich Roll: Right, sleep on a problem. But it has a very strange and elusive relationship with memory. Like memory doesn't seem to really be required for this, right, like sometimes, you will remember some of this stuff and then it fades, but nonetheless, the brain is doing its job in that state and you're able to come up with a creative solution or solve a problem that has defied you the night before. Dr. Walker: Yeah, and I have another it's probably second only to the idiocy of my idea that we never evolved sleep, that it was from sleep that wakefulness emerged that we started at the top of the podcast. The other stupid theory is that, in fact, we remember all of our dreams. Most of us when we wake up, if we can remember a dream, it's usually very difficult and different people have different dream recall strengths. The heart of that we try unlike the more unlikely it is. But I think that that's not a problem of memory imprinting. I think that's a difference in memory science that we call accessibility versus availability. I think when we wake up in the morning, we lose the IP address to the memory so we can't find it. It's availability is prevented. But I believe it's accessibility, it's still present there. Sorry I got that wrong. It's availability is still there, but it's accessibility is prevented. The reason why I think this is a tenable theory and I got some ideas as how to test it is because you can wake up in the morning, think, oh, I was having this incredible dream and you just can't bring it back to mind and you think, okay, it's just gone. Then two or three days later, you're walking down the street and you see a sign or you're in the shower and you see the shampoo bottle and all of a sudden there's a queue that triggers the unleashing of that dream memory and it all comes flooding back. In other words, that memory was there all along. You just didn't have accessibility to a still yet available and present memory. Now, if that's true, what it could mean is that we store all of our dreams. The reason I find that sort of hand waving wacky and fun philosophically to think about is we know that memory operates largely in a non-conscious manner. You can, for example, if you're walking up a set of stairs and you've got your pad of paper and you've left a drink on the stairs, you're reaching down to pick it up. That's an immensely complex challenge. You had to sort of compute the physics of where your hand was. You had to know what the weight of that cup was. This is all based on memory and it operates way below the radar of consciousness. Most memories do, if that's true, that our behavior is certainly influenced non consciously by our memories. It's what we call implicit memory, and we remember many of our dreams. Then all of a sudden it becomes interesting to ask how much does our waking life reflect or is shaped by our stored dreams in an unconscious way. Now, this is getting very Freudian, and I have to say I'm not a big advocate of Freud. I think he did a remarkable service to the science of sleep. He brought dreams into the world of the mind before it was in the Greeks, it was coming from Gods, hypnosis. Some those, Morpheus and then Chinese cultures had an idea that dreams came from the soul. But it was Freud who actually placed dreaming squarely within the mind. In other words, Freud made dream science a domain of brain science of neuroscience. Now, after that, it all kind of went south, and I often joke that I think Freud was 50% right and 100% wrong. Rich Roll: It only got into the interpretation. Dr. Walker: Exactly and we've demonstrated that it's why it's no longer embraced by the scientific community as a scientific hypothesis, because it's untestable, it has no solid predictions. I think it's good to keep in mind that there are some reports that at the time Freud was doing enough cocaine to kill a small horse when he was coming up with some of that, too. Rich Roll: Maybe you wanted to go back to cocaine? Dr. Walker: Yeah, I know. Well, I can't seem to get away from it. I think I have this enamored theory about dreaming and it's just not very fundable, so it's hard to get there. Rich Roll: I mean, I think it's the ultimate unknown terrain and it's just unbelievably fascinating. I like the idea that our brain is so complex and it's performing this mystical dance and computation while we sleep. The extent to which we barely begin to understand what that's all about, I think is just super interesting. Dr. Walker: I mean, and you mention this very early on in our taping, about dreams is another very strange state because last night you and I both became flagrantly psychotic. Rich Roll: Right. Dr. Walker: We did that multiple times throughout the night. Now, before you dismiss my kind of diagnosis of our nighttime psychosis, I'll give you five good reasons. Firstly, when we went into dream sleep, we started to see things which were not there, so were hallucinating. Second, we believe things that couldn't possibly be true, so we're delusional. Third, we get confused about time, place and person so we're suffering from disorientation. Fourth, we have wildly fluctuating emotions, something that psychiatrists call being affectively labile. Then how wonderful, you and I woke up this morning and we forgot most, if not all of that dream because we were paralyzed from amnesia. Rich Roll: We were paralyzed throughout. Dr. Walker: Many people don't realize this, that when you go into dream sleep, your brain paralyzes your body so the mind can dream safely so you don't act out your dreams. The parts of the brain that actually control the different stages of sleep in part or deep down within the brainstem. Now, when the brain is ratcheting up, it's upstairs activation of the brain for REM sleep for dreaming. It sends another signal down along the spinal cord and it paralyzes what are called the alpha motor neurons in your spinal cord. These control all of your voluntary skeletal muscle. When you deliberately want to move your hand, move your foot, sort of change your mouth, speak, etc., you are locked in physical incarceration during REM sleep, you are imprisoned within your own body. Rich Roll: When you have that, or I should say, when I've had these experiences where I'm being chased or something's happening and I feel like I'm stuck in molasses or I want to scream and I'm like, I generally will like the next morning she'll be like, you are making the weirdest noises and I'll have some memory that will trigger a memory. Like I was being pursued and I was trying to get away and I couldn't, and I was screaming out for help, but I couldn't even make a noise. Dr. Walker: That's exactly why it's such a good sign to do what it is. Rich Roll: Is sleepwalking then a malfunction and that paralytic system, like what's happening when you're sleepwalking? Dr. Walker: No, so sleepwalking, sleep talking, they’re a group of disorders called Parasomnia, which sort of essentially means just disorders that happen around sleep; para, meaning around. Sleepwalking and sleep talking actually don't come from REM sleep. You would imagine that they do and it's a very logical thing. In fact, what happens is that when we are in deep sleep, for reasons that we don't quite yet understand, but it may be that there's a jolt of nervous system activity and all of a sudden your brain raises or it tries to raise from the basement of deep sleep all the way up to the penthouse of wakefulness, but it gets stuck somewhere in between the 13th floor, for example. What’s strange, we can do this in the sleep laboratory where we've got these electrodes and what we're seeing outside in terms of the brain waves is deep sleep. But when you look at the camera, all of a sudden the patient is out the bed and the sort of moving around. If you wake someone up who's having a sleep walking or sleep talking event and you say, what was going through your mind, they will usually won't tell you anything. Rich Roll: Right. Dr. Walker: The reason is because they're in deep sleep, but not in dream sleep. Rich Roll: So interesting. Yeah, I have some epic sleepwalking stories from when I was a kid. I went out, I got up in the middle of the night and went outside in the middle of a thunderstorm and like walked a block away from the house and told my dad discovered, when I woke up standing in the middle of the street in a downpour. Dr. Walker: There are some remarkable case studies, some of which I discuss in the book where people have these episodes and some dangerous and some unfortunate things really happen. Rich Roll: Then, I just grew out of it. Like, how normal is that? Dr. Walker: It's very normal. The incidence of sleepwalking and sleep talking is far higher when we’re kids and most adults will grow out of it. Not all adults, but most adults will grow out of it. It's not really a sleep disorder necessarily. I think and again I'm not a clinician. I'm not trying to pretend to be a sort of a doctor in any means. But I think the general advice is if it's not causing you distress and it's not putting you in harm’s way, then one may not need to worry about it if it's sort of infrequent. But if it is causing you distress and it is putting you in harm’s way, then you can go see your doctor. I should note, by the way, something to on those sort of five tips and I should mention, walk it out, just which is the last one. None of those tips are really going to help anyone who has insomnia or sleep apnea. It's like me being your performance coach. I can give you all sorts of tips to optimize your performance. But if you've got a broken ankle, none of those tips are going to help you. We've got to get you to a doctor, treat the broken ankle, and then we come back to sort of optimizing your sleep so that the tips I'm giving out just that. Rich Roll: Right. I understand. But what percentage of people are truly insomniacs versus people who have habits that prevent them from getting a good night's sleep and call themselves insomniacs? Dr. Walker:It's actually very difficult to tell because part of the treatment for insomnia, which is now no longer sleeping pills, the first line treatment has to be something called cognitive behavioral therapy for insomnia or CBT for short. One of the things that works towards so as you can tell by the name Cognitive Behavioral, there is an aspect where we work on the mind and we work around your beliefs and your expectations and your understanding of sleep. That's the cognitive part of CBT. The behavioral part is actually asking what behaviors are you engaging in that are harming your sleep and what things are you not doing behaviorally that can help you sleep - alcohol, caffeine, regularity, light, etc.? Those do play a role, but usually it's much more of a combination of different things. With CBT, it's a much more extensive than that. It's just as effective for sleeping pills in the short term, much more effective in the long term. Unlike sleeping pills, when you stop working with your therapist, the benefits of CBT cognitive behavioral therapy for insomnia lasts for up to five years. But for sleeping pills, when you stop using them, not only do you typically go back to the bad sleep you’re having, you actually have even worse sleep. It's called rebound insomnia caused by these medications. Rich Roll: Yeah, I have friends who are in recovery for Ambien and the stories they tell are just harrowing. Dr. Walker: Yeah and there is a time and a place for those medications. They're usually recommended for acute short term significant episodes. Let's say that you're really struggling with a trauma or bereavement or something along those lines. Then in combination with therapy, they can be advised for short term use, the problem is most people aren't using them in a short term use model. The reason in part I know is I think it took George Lucas about 30 or 40 years to amass something like two billion in profit from the Star Wars franchise That took Ambien less than 24 months to do and so we can't do that with acute use. Again, sleeping pills have been associated with high risk of death as well as cancer. Do we know that's causal or not? No, we don't right now. I can make an argument as to why it may not be causal, but I can also make a scientific argument as to why it is causal. We probably won't ever find out because based on the association between mortality risk and things such as cancer and sleeping pill use, it's probably going to be unethical to do a study where you put people, healthy people on sleeping pills for several years because of the risk. Rich Roll: Yeah, no way. There's no way you could ethically justify that. Dr. Walker: No. Rich Roll: Yeah, we've been going on almost three hours now. But I can't let you go. I do want to ask you before I let you go, I know that you work with Google and I'm interested. Dr. Walker: I used to work with Google. Rich Roll: You used to work, okay, in that capacity, were you able to help them implement certain policies? Like what kind of transpired there in terms of the work culture that was going on and the impact that you work out on that culture? Dr. Walker: Yes. I was actually working with a part of Google that was called Verily, which is sort of that was the Google health. I wasn't really focused on going into there and changing the culture. It was more about developing either technologies or it was also they have some remarkable studies and that they’re public about this. There's some aspects that I can share where they're looking at how things such as sleep impact different aspects of human health so that they're doing wonderful things in trying to augment things like diabetes risk, cardiovascular risk. I think what they realized is that when you're looking at all of these disease states, based on everything we've spoken about for the past three minutes, which now is now three hours talking about time dilation. Rich Roll: Right. We're having our own inception, we are dreaming. Dr. Walker: I'm going to wake up and the alarm goes off and I thought, oh, I'm so sad. I thought I was on the Rich Roll podcast. Rich Roll: It's tomorrow. Dr. Walker: Yeah and knowing how critical sleep is, the foundation, they realized that there had to be some component of sleep appreciation within that framework of everything that they were trying to do. I was so fortunate enough to be able to do that and I no longer work with them. I've got a couple of startups that I'm now advising and working for. That was really I think, the push there, which was that sleep is the tide that rises all the other health boats. I remember when I was sort of speaking with them I almost have this analogy where if you think about a music studio and those recording desks with all of those dials and you can sort of mix and just sort of tweak them, what we're doing in health is trying to sort of go to individual dials. We're trying to manipulate cardiovascular health or change immune health or change metabolic and diabetes, health. But there's that one sort of dial all the way over to the left that if you move it all the way up, all of the other dials go up as well. Rich Roll: The master dial. Dr. Walker: That sleep is the Archimedes lever. If I think if I were to have something, a single sentence, I would say that sleep is the single most effective thing that we can do each day to reset the health of our brain and our body. Rich Roll: That would be a beautiful place to end this. But I just realized there's an important thing. We also didn't talk about that I would like you to touch on quickly. Dr. Walker: Yeah, of course. Rich Roll: Which is you talk to at the outset about what happens when you get a flu shot and you're sleep deprived. We're still in the midst of this pandemic,we're slowly emerging out of it. But can you talk a little bit about what you've learned about sleep, covid, immunity and how people should be kind of thinking about how their relationship with the virus? Dr. Walker: Yeah, so I'll speak about sleep and immunity sort of more generally and then come on to sleep Covid. Because sleep has changed in at least four different ways because of Covid - quantity, quality, timing and dreaming. I'll try to mentally put those stickies up on my cerebral wall so I come back to them, but in terms of sleep and immunity, there is a very intimate association between your sleep health and your immune health. Firstly, what we know is that individuals who report sleeping less than seven hours a night are almost three times more likely to become infected by the rhinovirus, which is the common cold. Second, we know from a prospective study in I think it was well over 30,000 women. Women sleeping five hours or less a night are more than 60% more likely to develop pneumonia across a five year period, which, of course, is a critical part of the Covid mortality equation. We've also mentioned that statistic about if you're not getting sleep in the week before you get your flu shot, you can't produce the normal antibody response. Do we know that that's the case for Covid yet? No, we don't. But we're looking at that. We also know it's the case for hepatitis A, hepatitis B vaccination too. I think there's an interesting case to be made that it could make a difference. We also know that just as we mentioned before, just one night of short sleep just four hours will drop those critical anticancer fighting cells, natural killer cells, by 7%. If that's true, then why what is sleep doing for our emotional health and sleep provides us with that for our immune health. It provides us two different benefits. Firstly, it's during sleep and particularly during deep sleep, where the body will be stimulated to produce many more of those critical immune factors. Even better, the sleep will actually increase the sensitivity and the receptivity of your body to those increased immune factors. You wake up the next morning as a more robust immune individual; sleep will restock the weaponry in your immune arsenal. On that basis, I think deep sleep has become very relevant in this pandemic. How is sleep changed right now? Well, as I mentioned, firstly, the studies show on average, which may be surprising to some people, sleep duration has actually increased somewhere between about 20 to 30 minutes, if you look at the handful of studies that show up. Rich Roll: People aren’t commuting. They don’t take their kids to school. Dr. Walker: That's the first issue. Now, if you look at that data a bit more closely, it's not that clean cut or straightforward. There is a cloud of data of people for whom sleep has actually become worse. People have lost their jobs. People don't know if they will still have their jobs. People are just very anxious about the pandemic. All of those things will decimate sleep, of course. Sleep quantity has changed. Sleep quality has changed also. But we also know that sleep timing has changed. How are you getting that extra sleep? Well, people are going to bed a little bit later, but they're waking up significantly later. I think this comes back to our discussion of chronotype. No covid, because we don't have to commute and wake up or do early morning meetings or get the kids to school. Many people have been able to sleep back in synchrony with their natural chronotype. It's revenge of the night owls right in that way. Then the final component is that people and I think we don't yet have enough data, but there's too many people saying this, that they were dreaming more and dreaming more about covid. Why would this be? I think there are two logical explanations. The first, just as we mentioned before, the later that you sleep into the morning, the more you go into that REM sleep rich phase. You’re just giving yourself probabilistic chance statistically of having more dreams. But I don't think that's the entire explanation. We also have spoken about this idea that REM sleep provides this form of emotional first aid, its overnight therapy. In fact, there's an American entrepreneur, E. Joseph Cossman, who had this lovely line. He said that the best bridge between despair and hope is a good night of sleep. I think when we're going through these difficult emotionally upheaval, time of a pandemic, no wonder the brain is trying to self-medicate it. This emotional situation with the thing that it knows provides a nocturnal soothing balm, which is this thing called REM sleep and dreaming. I think that's probably another explanation as to why we're not just dreaming more, but we're dreaming about the pandemic itself. Rich Roll: Trying to make sense of it, trying to process it. Trying to figure out a way to have a healthier relationship with it. Dr. Walker: That’s right. Sleep divorces some of the emotions from the memory, so that you come back the next day and you will better about those emotional experiences. Because sleep has essentially stripped the bitter emotional rind from the informational orange. It’s not as though you wake up and you don’t remember that emotional experience, you do. But it’s no longer as emotional as itself. It’s not time that heals all wounds, it’s time during sleep and specifically during dream sleep that provides emotional convalescence. Rich Roll: On the immunity subject, it would be interesting to do an evaluation of people that got covid, how severe their case of covid was and track that unto their sleep habits and patterns. Dr. Walker: People are doing that, we’re also looking when you get vaccinated, one of the consequences some people are describing are disruptions on sleep. Usually, what will happen is that you will get some degree of fever and when you’re going through fever that increases your core body temperature. When your body temperature increases, you’re not going to get a good sleep. There are some devices, I wear the aura ring and some sort of disclosure, I advise that take anything I say with a grain of salt. I’ve worn just any sleep tracking device and there’s this one for me, was a sticky device and I liked it. I was wearing it for 2 years before I decided to join the company. But they have a fascinating model, what they’ve been able to find because the aura ring, unlike many of these other devices, it tracks temperature. What they were finding is that in some people who went on a day or two days later to find out that they tested positive for covid, there was this spike in their relative temperature. We’re now starting to explore this idea that it could be a useful diagnostic tool, preemptive. Rich Roll: I mean, I got the Whoop on and they manage to knock your temperature but through the metabolic rate. They have some interesting signs on that as well. It’s cool how these wearable’s are sort of developing and how the technology is evolving. We’re now beginning to understand the significance that they can play. Dr. Walker: Exactly, I think I mentioned this invasion of technology into the bedroom and it has the deleterious force. But perhaps, unlike some other sleep scientist, I’m not puritanical about technology. That genie is out of the bottle and it’s not going back in anytime soon. If you want to rail against it, you’ll lose. But what we’re now seeing is this beautiful sort of cycle where technology is starting to solve some of the problems of technology. Like in the line in the Matrix, right? Programs hacking programs. It’s technology starting to hack the ills of technology. I do think that wearable technology has a part to play and a place in self-future health, this idea of personalized medicine and for me, I’m interested in personalized sleep medicine. That’s why I’m developing some sort of these companies. But I also think that we need to be a little more careful, now something called orthosomnia which is a sleep disorder caused by obsessive sleep tracking. Where you become so anxious, it seems to be maybe 10% to 15% of people who are using these suffer. By the way, ortho means straighten in medicine; you have orthopaedics, orthodontics, straightened teeth, straightened bones. Here, it’s about people getting too concerned of getting sleep straight, orthosomnia. Rich Roll: Yeah, I mean 100%. I think they’re just tools, it’s about your relationship with health, if you become obsessive about them, they work across purposes with their intent. Like I know there are certain days where I’m not sure if I really want to look at the Whoop score is because I have stuff to do. If it says like I’m not ready for it, that’s going to will screw me up. I just would rather, I’ll check it later. I think for me, my relationship to them is more in the macro, like I can look at trends over time. Or I play a game where I wake up in the morning and I’ll think, I’m pretty sure here’s where I’m at and I’ll check it and that helps me calibrate my intuitions around these things. The more intuitive of you are about them, the less reliant upon them I think you become. But you have to hold them a little bit lightly. Dr. Walker:I love that, I think that’s a beautiful way to think about it. I would often say to people like I had this really bad night of sleep, I don’t want to look at my ring. Firstly, everyone has a bad night of sleep. Don’t worry about it, it’s not the end of the world. The second thing, when it comes to trackers in particular with sleep follows weekly or monthly trend lines. Don’t follow nightly headlines, don’t worry about those things. I believe sleep tracking is a little bit different from other health wearable tracking. When I go to the gym, I kind of know when I get a good workout in or if I didn’t. When I be eating throughout the day,I know if I have been eating clean, in a healthy way or if I haven’t. Rich Roll: You don’t want to score on that? Dr. Walker:I think I would probably know it but I am ashamed of it. But what’s interesting about sleep is that for the most part it’s a non-conscious process. If I were to ask you, Rich last night how did you sleep, you can tell me. But if I said to you, Rich how was your sleep last Tuesday? By yourself, you probably don’t know. But that’s where I think the power of this technology, it can identify trends and patterns and if we can start to measure those and then intervene to give people useful tips what they should do in a personalized manner. Because everyone is sleeping poorly for different reasons, that’s really where we unleash the power of these things. Rich Roll: Matt Walker we got to end this thing. So great talking to you, will you come back and talk to me sometime? Dr. Walker: If you would have me and your listeners don’t lose the will to live because of my inane voice, I would be delighted to come back. Rich Roll: You are a gift my friend. The work that you’re doing, I think it’s super important. It’s a privilege and an honor helped amplified a little bit. I really appreciate what you do, it’s a great act of service to humankind so thank you for that and thank you for spending the afternoon with me. Dr. Walker: I say exactly the same thing back to you based on what you’re doing. Your honesty and your vulnerability of story has impacted people I know. What you’re doing with this movement around and with podcast and empowering mind, body, guidance and information I think it’s fundamentally critical. You are a gift, now I anoint you as a sleep ambassador. Rich Roll: Now the pressure. I’ll have a terrible night of sleep tonight. I’ll be anxious about that. Dr. Walker: Put me on sleep dial, I’ll help you. Rich Roll: I’m going to call you every night, am I doing this right? Dr. Walker: Yeah, don’t worry I will be right there for you. Thank you so much for having me, Rich. Rich Roll: You can find and learn about Matthew at the Sleepdiplomat.com Dr. Walker: Yes, at the sleep diplomat, or if you want you can read the book which is called “Why We Sleep”, you don’t have to read the book, you can just buy the book, that’s what the publishers tell me. Rich Roll: No, you got to read it. Trust me. Dr. Walker:You can just buy a used copy. Rich Roll: It changed my life. Dr. Walker: Aside from the monetary stuff, if you’re interested in learning more about sleep, the book is a good way to do it. Rich Roll: Good, well let’s do this again sometime. Dr. Walker: I hope so. Thank you, Rich. Rich Roll: All right. Peace. [END OF TRANSCRIPT]