#48–Matt Walker, Ph.D., on Sleep (Part 2 of 3): Heart disease, cancer, causes of sleep disruption...

1. 0:00 – 0:04

   Intro

   1. PAPeter Attia0:00

      [intro music]

2. 0:04 – 11:13

   Daylight Saving Time and Sleep's Link to Heart Disease

   1. PAPeter Attia0:04

      Hey everyone, welcome to The Peter Attia Drive. I'm your host, Peter Attia. The Drive is a result of my hunger for optimizing performance, health, longevity, critical thinking, along with a few other obsessions along the way. I've spent the last several years working with some of the most successful top-performing individuals in the world, and this podcast is my attempt to synthesize what I've learned along the way to help you live a higher quality, more fulfilling life. If you enjoy this podcast, you can find more information on today's episode and other topics at peterattiamd.com. [upbeat music] Hey everybody. Welcome to this week's episode of The Drive. I'd like to take a couple of minutes to talk about why we don't run ads on this podcast and why instead we've chosen to rely entirely on listener support. If you're listening to this, you probably already know, but the two things I care most about professionally are how to live longer and how to live better. I have a complete fascination and obsession with this topic. I practice it professionally, and I've seen firsthand how access to information is basically all people need to make better decisions and improve the quality of their lives. Curating and sharing this knowledge is not easy, and even before starting the podcast, that became clear to me. The sheer volume of material published in this space is overwhelming. I'm fortunate to have a great team that helps me continue learning and sharing this information with you. To take one example, our show notes are in a league of their own. In fact, we now have a full-time person that is dedicated to producing those, and the feedback has mirrored this. So all of this raises a natural question. How will we continue to fund the work necessary to support this? As you probably know, the tried and true way to do this is to sell ads. But after a lot of contemplation, that model just doesn't feel right to me for a few reasons. Now, the first and most important of these is trust. I'm not sure how you can trust me if I'm telling you about something when you know I'm being paid by the company that makes it to tell you about it. Another reason selling ads doesn't feel right to me is because I, I, I just know myself. I have a really hard time advocating for something that I'm not absolutely nuts for. So if I don't feel that way about something, I don't know how I can talk about it enthusiastically. So instead of selling ads, I've chosen to do what a handful of others have proved can work over time, and that is to create a subscriber support model for my audience. This keeps my relationship with you both simple and honest. If you value what I'm doing, you can become a member and support us at whatever level works for you. In exchange, you'll get the benefits above and beyond what's available for free. It's that simple. It's my goal to ensure that no matter what level you choose to support us at, you will get back more than you give. So for example, members will receive full access to the exclusive show notes, including other things that we plan to build upon, such as the downloadable transcripts for each episode. These are useful beyond just the podcast, especially given the technical nature of many of our shows. Members also get exclusive access to listen to and participate in the regular Ask Me Anything episodes. That means asking questions directly into the AMA portal and also getting to hear these podcasts when they come out. Lastly, and this is something I'm really excited about, I want my supporters to get the best deals possible on the products that I love. And as I said, we're not taking ad dollars from anyone. But instead, what I'd like to do is work with companies who make the products that I already love and would already talk about for free and have them pass savings on to you. Again, the podcast will remain free to all. But my hope is that many of you will find enough value in, one, the podcast itself, and two, the additional content exclusive for members to support us at a level that makes sense for you. I want to thank you for taking a moment to listen to this. If you learn from and find value in the content I produce, please consider supporting us directly by signing up for a monthly subscription. Welcome back to the three-part series on sleep with Professor Matthew Walker, professor of neuroscience and psychology at the University of California, Berkeley, and the founder and director of the Center for Human Sleep Science. Matthew earned his undergraduate degree and Ph.D. in neurophysiology in London and subsequently became a professor of psychiatry at Harvard Medical School before moving to Berkeley. His research examines the impact of sleep on human brain function in healthy and diseased populations. To date, he has published over 100 scientific studies. He has received numerous funding awards from the National Science Foundation, National Institutes of Health, and he's a fellow of the National Academy of Sciences. He's the author of the international bestseller Why We Sleep, which also happens to be the favorite book of my not yet two-year-old son. He holds many patents covering various consumer-based sleep recordings, sleep tracking, and sleep simulation. He's a sleep scientist at Google, where he helps the scientific exploration of sleep in health and disease. He is also an enormous fan of Formula One and my hero, Ayrton Senna. And in the third part of this installment, we actually spend quite a bit of time discussing this. In the second part of this series, we discuss sleep and cardiovascular disease, sleep and how it affects diet, sleep and reproductive function, the risk of deliberate sleep deprivations, sleep and cancer, the lack of sleep within the medical profession, school start times and sleep deprivation, sleep patterns and light, the biochemistry of sleep and naps, the efficacy of various medications on sleep. As a reminder, at the end of this series, we're going to take questions for a follow-up AMA with Matthew. Asking questions on the AMA forum and listening to the AMA podcast with Matthew, along with all AMAs, will only be available to subscribers. So if you haven't signed up yet, you can do so now at peterattiamd.com/subscribe. So without further delay, here is part two of three with Professor Matthew Walker. [upbeat music] Okay, there's like literally 100 more things I want to ask you about. So can you make the case for why cardiovascular disease is worsened by or accelerated by sleep deprivation? And then same question I'm going to ask you in a moment for cancer. Just pick the best, like-

   2. MWMatthew Walker6:24

      Yeah

   3. PAPeter Attia6:24

      ... because again, you could write a book on each of those topics.

   4. MWMatthew Walker6:26

      And we can go into sort of de-

   5. PAPeter Attia6:27

      Yeah, yeah

   6. MWMatthew Walker6:27

      ... and, and the book, but let me just give you one example for cardiovascular disease. There is a global experiment that is performed on 1.6 billion people across 70 countries twice a year, and it's called daylight savings time. And what we've seen is that in the spring when we lose an hour of sleep, there is a subsequent 24% relative increased risk for heart attacks that following day, 24%. In the fall, when we gain an hour of sleep opportunity, there is a 21% reduction in heart attacks that following day.

   7. PAPeter Attia7:01

      How long has that been known? I mean, I remember the first time I saw that, I was like, "That can't be right."

   8. MWMatthew Walker7:06

      And you know, when you see it bidirectionally like that, it's very diff- you know, that seems like a very robust manipulation. That's been known for probably about 10 years. What's also interesting and, and I won't get away from cardiovascular disease, don't worry, but just simply to mention that when you look at that same transition, you see the same profile for car accidents, you see the same profile for suicidal attempts and suicide completion as well. What's also interesting, by the way, is that you see it in terms of, um, federal judges handing out harsher sentences. They hand out harsher sentences on the Monday after that time change in the spring because they're more moody, emotionally irrational, and less sort of, you know, empathetically sensitive because of that one hour of lost sleep and in the fall, more lenient sentences. So I can-

   9. PAPeter Attia7:59

      And does this effect last for two or three days until-

   10. MWMatthew Walker8:02

       So there is a blast radius to it-

   11. PAPeter Attia8:03

       Yeah

   12. MWMatthew Walker8:04

       ... that you can see it, that it's better, but still worse in the spring, which is where you s- you lose that hour of sleep. The effect is still worse on the, the second day, and it's almost recovered by the third day, and finally comes back to what looks like a baseline by about day four. So there is a blast radius, and this is, you know, b- b- blows my mind-

   13. PAPeter Attia8:23

       You know why I find this interesting, by the way?

   14. MWMatthew Walker8:24

       ... just one hour of sleep.

   15. PAPeter Attia8:25

       Yeah. And, and here's the other thing I always found amazing about that statistic. In the northern hemisphere, you would predict the opposite if sleep were irrelevant, right?

   16. MWMatthew Walker8:34

       That's right.

   17. PAPeter Attia8:35

       Wouldn't you think that gaining that hour of sunlight in the day in the spring, just the overall anticipation, I mean, there's virtually no one in the northern hemisphere that isn't happier-

   18. MWMatthew Walker8:46

       [laughs]

   19. PAPeter Attia8:46

       ... in April than they are in November, right? So, so it's almost like you have all of that positive stuff working against you-

   20. MWMatthew Walker8:53

       It gains the effect

   21. PAPeter Attia8:54

       ... and you still see the signal you just described.

   22. MWMatthew Walker8:56

       Still see it. Yeah. So in the face-

   23. PAPeter Attia8:57

       It's like a kick in the face.

   24. MWMatthew Walker8:59

       Yeah, so in the face of birds chirping, sunlight streaming, temperature warming, that one hour of lost sleep will still you put, put you back on your derriere rather quickly in terms of all of these facets. So there's one example for cardiovascular disease. Another one, there was a fascinating study where they took a group of otherwise healthy middle-aged adults who had no sign of coronary artery disease, and then they tracked them for five years, and then they looked at how much sleep that they were getting. So again, hands up, this is essentially an associational longitudinal prospective study, and it's, you know, you can't derive causality from it. But what you can certainly say is when they started, they had no signs of calcification of the coronary artery. Those people in that study at the end of the five years who were getting five hours of sleep or less had a 2 to 300% increased risk of calcification of the coronary artery, which is the main corridor of life for your heart. If you have a massive coronary, essentially when you hear that colloquially, you know, that's essentially what's happening there. So that you could have that calcium buildup on the basis of being bucketed into insufficient sleep, that tells me that it's not that when you are insufficiently slept, you also are someone who has calcified arteries. It is saying that if you are insufficiently sleeping, you are increasing your risk for developing that condition. This is about the development of that, but-

   25. PAPeter Attia10:33

       Now how hard is it to control that for some obvious things that would track with that? For example, shift workers or people of lower socioeconomic status who are working three jobs, and all the other things that can work against you.

   26. MWMatthew Walker10:45

       So you can't so, so there are exclusion, there are some great exclusion criteria in that study where they prevent those participants from entering the study. They also then added in other factors that you could imagine would lead to that, so they controlled for those, things like exercise, BMI, neck circumference, smoking. They even include history of snoring, so they tried to take sleep apnea out of the equation, and still that relative risk was significantly larger.

3. 11:13 – 16:50

   Sympathetic Overdrive as the Core Mechanism

   1. PAPeter Attia11:13

      What do you think is the mechanism?

   2. MWMatthew Walker11:15

      I think the mechanism is probably several-fold. I think the first thing that we see when we under-sleep people is that they become much more sympathetically nervous system driven. Now, that to some people may sound, oh, that sounds like a good thing. No. You have two branches of your automatic nervous system-

   3. PAPeter Attia11:35

      I, I swear w- for a moment I thought you would say good knowing that the listener would understand that they're sympathetic and parasympathetic, but thinking you were, you were gonna make a comment about being more high-strung is better because... But no, you actually were making a jo-

   4. MWMatthew Walker11:49

      I, I mean, I think, I think-

   5. PAPeter Attia11:50

      You're so well-tuned to this

   6. MWMatthew Walker11:52

      ... I think that's the, the beauty. My IQ is so low, I'm s- such a, a simpleton that I can always revert to the naive state, and I, I don't have to make assumptions. That's the beauty of my idiocy. But no, sympathetic nervous system being sort of cranked on your sympathetic nervous system is not a good thing Your sympathetic nervous system essentially is your fight or flight branch of the nervous system. And what we find is that as soon as you start to under-sleep an individual, that fight or flight branch of the nervous system starts to ratchet up. When that increases, you start to see, or perhaps the reason why it increases, is that you get a greater amount of adrenaline release, you get a high spiking in levels of cortisol, you get a blunting in growth hormone. And I think probably just the cortisol and the growth hormone alone may set you on a path towards cardiovascular disease because we know that those are two factors that lead into that, sort of some of that atherosclerotic sort of equation.

   7. PAPeter Attia12:54

      And, and that brings it back to, uh, Alzheimer's disease, which is even if you just look at the epidemiologic data, the signal's quite large on the benefits of IGF and growth hormone more than any other disease in protection from neurodegeneration. So that may be even in addition to everything you talked about with respect to clearance, you're simply taking away neurotrophic factors-

   8. MWMatthew Walker13:16

      Correct

   9. PAPeter Attia13:16

      ... that are essential.

   10. MWMatthew Walker13:17

       There's some data, and I don't know how well replicated it is, I just read it in one study, where if you look if you're APOE4, so this is in terms of your genes, there are some genes that can predispose you to Alzheimer's disease. On this podcast, there are wonderful descriptions of going into all of the details of these. But APOE4 significantly increases your risk for the development of Alzheimer's disease, it appears. But what's interesting is that if you are APOE4 but you are normotensive, you don't necessarily have an increased risk of Alzheimer's disease. If you are APOE4 but you are hypertensive, then your Alzheimer's disease risk is far higher. So in other words, there seems to be an interaction, a gene by cardiovascular disease interaction that leads that genotype f- to predispose you to Alzheimer's disease. And therefore, you know, if you are under-sleeping, you are putting yourself on a path towards many new different factors that we are learning regarding cardiovascular disease. You know, calcification of the arteries is one of them. But we also just see, you know, blood pressure, you know, spike. We can take someone who is in a lovely state of, you know, normotensive profile and has been, and after either one night of total sleep deprivation or one night of short sleep, you know, uh, we can almost start to see it after about reducing sleep by three hours. Take someone down, down to five hours for just one night, you immediately see this spike in the fight or flight nervous system, blood pressure goes up, you start to see cortisol increase, heart rate starts to increase as well. You know, it's almost as though you've just got a beautiful car engine, you've put it in neutral, and you've put your foot on the gas pedal, and you're just revving the living daylights out of that engine in a fight or flight state. Now, if you do that chronically, which is what most people do with insufficient sleep, you know, day after day, week after week, year after year, decade after decade, it's not surprising that, you know, just revving the daylights out of that engine, at some point gaskets are going to start blowing. It's not designed to operate in that high-revving state all... Now, high-revving occasionally, just fine. And if you have a beautiful, let's say, you know, Mezger Porsche engine which loves to go to nine grand, and-

   11. PAPeter Attia15:44

       Of course

   12. MWMatthew Walker15:45

       ... you and I going-

   13. PAPeter Attia15:45

       As long as it's in the GT3. [laughs]

   14. MWMatthew Walker15:47

       I had to geek out on cars for a little bit 'cause I'm just so obsessed. I had to get it in there.

   15. PAPeter Attia15:51

       [laughs]

   16. MWMatthew Walker15:51

       But, but even then, you just can't stay at that RPM, that high RPM for very long. You just know it from listening to the engine. You just know that mechanical badness is happening in neutral when you've got your foot on the gas pedal. Well, that's the same way with chronic sleep deprivation in your nervous system. So I think many of the cardiovascular effects, in fact, I think we're writing a paper right now, I think if there is one central common pathway through which we can understand almost all aspects of the deleterious impact of insufficient sleep, it is through the autonomic nervous system and specifically an excessive leaning on the fight or flight branch of the nervous system, which is to say that your sympathovagal balance is way off and you are far more in that fight or flight sort of aversive state. So I think that to me is where that disease pathology starts and perhaps progresses from that point.

   17. PAPeter Attia16:50

       A-

4. 16:50 – 20:07

   Sleep Loss, Fuel Partitioning, and Dieting

   1. PAPeter Attia16:50

      and I think only adding to that, which is probably what you described is sufficient alone, but when you look at what I think are pretty well documented appetitive changes in people under sleep deprivation, and more importantly the inferior fuel partitioning that follows-

   2. MWMatthew Walker17:09

      Yeah

   3. PAPeter Attia17:09

      ... so the hyperinsulinemia, the impaired glucose disposal, the tendency to probably eat more crap. I mean, I'm at my worst when I am sleep deprived. It is, you know, I just, it's so hard to avoid junk food. Whereas probably the single greatest tool in my arsenal to eat well is to sleep well. I mean, it's, doesn't sound like that's an obvious thing, but it's amazing. What-

   4. MWMatthew Walker17:35

      When you, when you read the data, I mean, it's, it's striking and, you know, we can get into that, which is essentially what you've just described is the, the energy balance of an organism of a human being, and both the regulation of energy once you've taken it in, and also the input of the energy or, and the selection of the energy. How do you eat? And how much do you eat? And then secondly, once you've eaten, what does your body do with that food in terms of basic kind of blood sugar control?

   5. PAPeter Attia18:07

      And then the fourth thing is where do you access it? So y- I, I'm sure, I mean, I'm sure this has been done, I just haven't seen it, but if you look at respiratory quotient of people sleep deprived versus not, I'm sure RQ must be going up, right? I'm sure they're absolutely going after the wrong fuel partitioning.

   6. MWMatthew Walker18:22

      That's exactly what you see.

   7. PAPeter Attia18:23

      I'll do what you do well, but then I always forget to do. Let me explain why that matters. Respiratory quotient going up implies that under the same level of exertion, you would preferentially go after glycogen for ATP as opposed to fat. And so not only is that not what most people want, because they'd p- prefer to burn their fat than burn their glucose, it signals a metabolic inefficiency, which lays at the heart of all of this stuff.

   8. MWMatthew Walker18:49

      And a beautiful example of that is a great study that looked at the efficiency of dieting when you are underslept. And effectively what they found is that your diet is f- all for nothing if you're not sleeping well. Because what they found is that when you are underslept, defined as sleeping six hours or less, 70% of the weight that you lose will come from lean muscle mass and not fat. In other words-

   9. PAPeter Attia19:19

      Which is perfect when your cortisol is high. I mean, that's exactly what cortisol does

   10. MWMatthew Walker19:22

       ... that's exactly, so that's exactly what you'll see with cortisol. So in other words, your body becomes immensely stingy at giving up its fat. Your body will ruthlessly hold onto its fat when you are underslept and not give it away. Instead it will... So when you are underslept and you're losing weight, you're losing the thing that you want to keep, which is beautiful muscle definition, and you're holding on to the one thing you're trying to get rid of, which is the blubbery fat.

   11. PAPeter Attia19:50

       And it's really everything. It's the cortisol is working against you, insulin will work against you. You're gonna have more hyperinsulinemia. You will have more catecholamines working against you.

   12. MWMatthew Walker19:58

       Correct. Yeah, we see that with norepinephrine in particular.

   13. PAPeter Attia20:01

       Oh, and testosterone will go down. That's gonna work against adiposity, getting rid of it.

5. 20:07 – 24:04

   Sleep and Reproductive Health

   1. MWMatthew Walker20:07

      Yeah, I should note by the way that, you know, men, and we, w- I think we'll come onto this later, but you know, men who are sleeping just five to six hours a night will have a level of testosterone which is that of someone 10 years their senior. So insufficient sleep will age a man by a decade in terms of that critical aspect of wellness and virility. So if you want to sort of be very, you know, bravado about insufficient sleep, be careful. I would also say that, by the way, we found it simply associational, but men who are sleeping just five hours a night have significantly smaller testicles than those men who are sleeping seven hours or more.

   2. PAPeter Attia20:41

      And I'm sure that in that you would see FSH and LH must be lower, right?

   3. MWMatthew Walker20:45

      So we do. So, you know, I'm not trying to make necessarily funny, even though sometimes I'll start talks that way just to sort of get the bravado folks out the way. But you also f- firstly see that you, men who are sleeping six hours or less will have fewer sperm. Those sperm will have more deformities. But this is not limited-

   4. PAPeter Attia21:03

      When you say deformities, even genetic, so even aneuploidy in the split?

   5. MWMatthew Walker21:06

      That's correct, yep, and you can see that in rats too if you do those studies, and those studies have been done with short sleeping rats. But it also transfers to women, that you see that women who are sleeping just five to six hours a night will have about a 20% reduction in FSH, which is called follicular stimulating hormone, which essentially is a critical part of the reproductive, you know, pathway in terms of getting pregnant. Women who are sleeping that little too typically have about a 30% higher rate of abnormal menstrual cycles. So if you put together a couple that is trying to conceive and that couple is on six hours of sleep, and you've got a man who's down on testosterone, down on the amount of sperm that they're producing, the motility of those sperm are reduced, and then the woman you, you're down on, you know, you've got erratic menstrual cycles, you've got FSH that's down too, from a reproductive standpoint, this is devastation.

   6. PAPeter Attia22:06

      And again, evolutionarily isn't that surprising. It's basically mother nature saying, "If the conditions are not optimized for you to sleep, it's probably not optimal for us to propagate the species at this moment."

   7. MWMatthew Walker22:17

      And that is r- probably something that rarely happens, and-

   8. PAPeter Attia22:20

      What happens to FGF21? Do we know?

   9. MWMatthew Walker22:23

      I was about to say we don't know. I, I should say I don't know of any studies that have looked at that. Um, they should-

   10. PAPeter Attia22:29

       FGF21 has such an interesting... It's one of the few places in the brain where you'll see a difference between men and women under a fasted state. So under a fasted state, you don't appear to see the same hit in reproductive fitness of a man, but you do see it in the woman. There's actually an anatomic reason for this that I, at this moment, am forgetting, but it basically has to do with this rise of FGF21, and you'll see basically the inhibition of FSH in the women without it in the men. Which again is like, it's this question of if, if food is scarce, we really don't want a mother to try to nurture another body.

   11. MWMatthew Walker23:10

       Yeah, maybe that's the biological warning beacon that just says time out on, you know, reproductive capacity right now.

   12. PAPeter Attia23:18

       I always get asked, is a ketogenic diet in any way good, bad, or indifferent towards fertility? And my answer is I actually have no clue, but just on first principles, it would seem that a ketogenic diet could have one negative side effect on the woman, which is exactly that, 'cause a ketogenic diet generally does put up FGF21. It could be offset by benefits. If you took someone who's metabolically ill, who is fixed by the ketogenic diet-

   13. MWMatthew Walker23:44

       That's it, yeah, it's disparate, yeah

   14. PAPeter Attia23:44

       ... it could offset it. But all things equal, yeah, you know, I certainly wouldn't recommend fasting for a woman who's trying to conceive. But you've had the luxury of spending a lifetime thinking about this. I'm sort of playing catch up over the past couple of years.

   15. MWMatthew Walker23:58

       By the way, it's one of the things that you do brilliantly, by the way, [laughs] from what I've l- I listen to on every one of your podcasts.

6. 24:04 – 34:33

   Why Evolution Left Us No Safety Net for Sleep Loss

   1. MWMatthew Walker24:04

      But But what I would say in response to your question, though, about that evolutionary question, the reason I suspect it rarely occurs, however, is the following. Human beings are the only species that deliberately deprive themselves of sleep for no apparent reason. You almost never see other organisms undergo sleep deprivation. The only time that you see another species de- uh, seemingly restrict its sleep is in under two conditions. The first is under certain, with certain mammals, after they've given birth, they will deprive themselves of sleep to care for their young. The most obvious example there is in killer whales, where the mother will break from what's called the pod, which is the main group. They will go away, and they will give birth, and then they will bring that calf back to the main pod, and during that time, they will short sleep. The second is under conditions of starvation, that when an animal starts to become starved, they will-- there is a wake promoting signal where you will actually stay awake longer, and it gives the animal the ability to forage in a larger perimeter because presumably the current perimeter is not containing sufficient food. And I think that that's the reason why some people will say when I undergo, you know, either time restricted feeding or especially when I undergo fasting, the reason that I feel like I don't need to sleep as much or, you know, I, and I feel more awake even though I'm sleeping less and it's great. I actually would be very cautious about doing that for long periods of time and doing it sort of repetitively for long periods of time is because there are still, you're still suffering the decrements of insufficient sleep. But the reason that you feel awake is because there is a biological mechanism in place that says, "Oh my goodness, if you're not getting food, we need to keep you awake for a little longer. We're going to sacrifice this thing called sleep for a little bit so that you can go and find more food." So there's a wake promoting mechanism, and we know how that works. But the more important point here being made, I think, for me is that because human beings are the only species that deliberately deprive itself of sleep, and no other species has really done that, it means that mother nature throughout the course of evolution has never had to face the challenge of sleep deprivation. So in other words, mother nature has never come up with any safety nets for any of our major biological systems, metabolic, reproductive, cardiovascular, immune, mental health. None of these things have any safe holding. They don't have any sort of crutches when sleep goes away. Why? Because mother nature's never been asked to solve that question. Now I'll give you an example-

   2. PAPeter Attia26:53

      I, I use the same argument, by the way, for sitting in chairs, you know, or, or, or-

   3. MWMatthew Walker26:57

      Oh, that's a great analogy

   4. PAPeter Attia26:57

      ... so many of these things that-

   5. MWMatthew Walker26:59

      Sedentary behavior is a great example

   6. PAPeter Attia27:01

      ... yeah, that we just, that we just do that we-- you could argue if our species could survive another hundred million years, maybe sitting around doing nothing, drinking soda, would-- we'd, we'd, we'd figure out a way to make that not so harmful, you know, assuming it interfered with, you know, our capacity to reproduce. If it didn't, then maybe evolution wouldn't take any interest in it.

   7. MWMatthew Walker27:23

      Yeah. But I mean, I think it's, it's the reason for me at least why an alternative example there in the pro would be, you know, an adipose cell, that mother nature throughout the course of our life and most species experienced times when there was feast and times when there was famine. And so mother nature faced with that challenge of famine came up with a solution called the fat cell, so that we could store caloric credit and then spend it when we needed to when we went into famine. Where is the adipose cell for sleep? Where is the fat cell for sleep? You know, wouldn't it be lovely if we could store up sleep credit and then spend it? And the answer is there is no such thing because the-- it's, there has never been the challenge in the course of evolution to come up with that solution and that-

   8. PAPeter Attia28:13

      Because hibernation is not an example, right?

   9. MWMatthew Walker28:15

      No, hibernation is-

   10. PAPeter Attia28:16

       Hibernation is the opposite

   11. MWMatthew Walker28:17

       ... very different.

   12. PAPeter Attia28:17

       Hibernation basically says it's not giving you credit to sleep less in the summer. It's just taking stock of the fact that there really is nothing for you to eat in the winter.

   13. MWMatthew Walker28:26

       Correct. And you-- that's, that's really about energy expenditure and essentially energy preservation and torpor and hibernation of different states to, to sleep itself. But that's always, I think, been something I've thought a lot about that example of, you know, the fat cell versus sleep. And it's the reason why people unfortunately think that sleep may be like the bank, that you can accumulate a debt during the week, and then you can just sleep it off during the weekend.

   14. PAPeter Attia28:54

       What's the name again for that phenomenon of the sort of Monday through Friday short sleeper who binge sleeps on the weekend? What's the-

   15. MWMatthew Walker29:01

       It's called social jet lag.

   16. PAPeter Attia29:02

       Social jet lag.

   17. MWMatthew Walker29:03

       Yeah. Where you sort of essentially, it's what I used to term very politically incorrectly as sleep bulimia, which was where you would essentially, you know, purge during the week, and then you just binge during the week, and it's this real binge-

   18. PAPeter Attia29:16

       Yeah

   19. MWMatthew Walker29:16

       ... purge kind of abstinence syndrome. The reason it's problematic is not just because sleep doesn't work like that, and the studies show that that's very deleterious to health, is because it also is terrible torture on your circadian biology. Because what happens is that you start to wake up, you know, you'll be going to bed at one, sort of one or, you know, midnight rather than nine, and then waking up at, you know, ten, eleven, you know, on a Saturday and a Sunday. And then come Sunday night, you've got to drag your body clock back by three hours, you know, to get into bed, and you repeat it the next weekend. That's essentially like saying to your biology, and it's no different, "I'm going to fly back and forth from San Francisco to New York every weekend," a three-hour social jet lag difference. That's a hazard ratio impact on your circadian biology that you-

   20. PAPeter Attia30:09

       And as I'm listening to you say this, I'm, I'm making the stronger and stronger case for my move to Austin, which in part is driven by just shortening the trips that I have to take. You know, to be able to only have to take a one-hour time zone delta or, you know, never basically having to take more than a two-hour time zone delta is, is-

   21. MWMatthew Walker30:29

       For your, for your lifespan, healthspan, for the impact that you can have on this pan- planet and this society during the time that you're here, and for the preservation of you in your children's life, I would strongly recommend it.

   22. PAPeter Attia30:47

       I'll share with you an interesting example of a patient of mine who has an example of what happens when that system, you know, quote-unquote, "breaks." So this gentleman, I'll try to be as vague as possible so I don't identify him even if he's listening, not that he would care if I told the story anonymously, basically worked in the finance sector, but at some point was living on the West Coast of the United States, but basically was exclusively involved in, you know, Eastern European markets. So you can imagine what time he had to be waking up to deal with that. After several years, and he in part moved from the West Coast to the East Coast to try to make that gap smaller, but he got to the point where he could never sleep past 3:00 AM. It was metaphysically impossible, regardless of what time. If he went to bed early, if he went to bed late, he was up at 3:00 AM. And it turned out one of my colleagues, Vic Jain, who's a, a Stanford trained sleep doc at Northwestern and also someone I just can't wait to interview because he's just so insightful on sleep, you know, he basically did something that you and I had talked about earlier, which was reverse use of melatonin and blue light to phase shift him into the correct time zone. And what humbled me about the story was how long it took to move, and it just gives you that sense of could you imagine forcing that on your system once a week?

   23. MWMatthew Walker32:10

       Yeah.

   24. PAPeter Attia32:10

       And I mean, it took months to correctly-

   25. MWMatthew Walker32:13

       Course correct that biology

   26. PAPeter Attia32:14

       ... to course correct. Yeah, to cor- now admittedly, it had been in place for a couple of years by the time, you know, I met him, so you, you know, you have a little bit more to overcome. But nevertheless, I was blown away at the lengths that Vic had to go to drag him forward by three hours.

   27. MWMatthew Walker32:32

       For that biology to have been tortured for that long, it's going to take a reset of, you know, non-trivial magnitude and help from exogenous agents like melatonin, like blue light, regular exercise, exposure to daylight. You know, even manipulations of body temperature it could take. So there are a whole arsenal of tools in the sleep doc kind of box that we can use to sort of make these manipulations either be it for people with insomnia, be it people with anxiety, be it people with sort of jet lag or what's called circadian phase delay, which is essentially what he was suffering from, which was-

   28. PAPeter Attia33:12

       You mentioned temperature. This was something I didn't know until I learned it through the, through this patient's case and through, through Vic's learning, which was, uh, about two hours before the wake up, you see this drop in temperature, and like that drop in this guy is occurring at 1:00 AM. He's getting that drop up and then... And so you, it-- what you basically were doing was dragging that thing to, you know, 4:00 AM.

   29. MWMatthew Walker33:36

       That's right.

   30. PAPeter Attia33:36

       You had to drag the temperature drop to 4:00 AM, and again, I think it just speaks to the complexity of this situation. And, and as a general rule, when you mess with really complex, hardwired, evolutionarily sound things, you've got to be careful or you're going to pay the fiddler.
7. 34:33 – 40:31

   Sleep, the Immune System, and Cancer

   1. PAPeter Attia34:33

      So let's talk about one more thing, which I'll, I, we could talk about cardiovascular disease for, for much longer, but let's talk about cancer and let's talk about when I talk about these diseases with patients, one of the things I try to do is say, "Let's reverse engineer what we think is happening when this disease goes wrong and then back things out." So when it comes to cancer, I say, "Look, cancer has a bunch of things that have to go wrong. First, you have to have a genetic insult. Two, it has to be missed by the immune system. And fortunately, most of the time our T cells can figure out that cancer is non-self, et cetera, et cetera." And you kind of walk through all of these things. So let's talk about the immune system for a moment because we know that if you're not s- well, I want to let you explain that. Yeah, I'll let, I'll let you go from there [laughs] because I, I was going to, I was just about to go off on this topic, but tell me about how sleep impacts the immune system and not only how that might impact getting common colds, but how it could impact cancer.

   2. MWMatthew Walker35:26

      So firstly, what we know is that there are now significant links epidemiologically between sleep and cancer of a variety of forms. Currently, that list includes cancer of the bowel, cancer of the prostate, and cancer of the breast, and then we can step down-

   3. PAPeter Attia35:40

      Which are basically three of the top four

   4. MWMatthew Walker35:43

      Uh, exactly, yeah, three of the heavy hitters. Next, you can sort of say, okay, h- what, what about the causal evidence? Well, firstly, I would say before I describe the causal evidence, that causal evidence is now so strong that recently the World Health Organization decided to classify any form of nighttime shift work as a probable carcinogen. Their words, not mine. And the proof of evidence that is required by the World Health Organization to make such a statement usually has to be Astronomical. And that data is now, I think, very well put in place. I'll just mention one quick causal manipulation study done by a colleague down at UCLA. They took a group of healthy adults, and they limited them to just four hours of sleep for one single night. And then they looked at a set of cells called natural killer cells. And you can think of natural killer cells like the Secret Service agents of the immune system in that they're pretty good at identifying dangerous foreign elements, one of which are malignant cancerous cells. Um, they'll inject some things into them and try and destroy them, essentially. So what you want is a pretty virile set of those immune assassins circulating in your body. And what they found is that one night of four hours of sleep reduction led to a seventy percent drop in natural killer cell activity. That's quite a surprising state of immune deficiency that has happened within one night. So you can step and repeat that and imagine what would be the state of your immune system, particularly for those critical anti-cancer fighting immune cells after several weeks, if not months, of insufficient sleep. That's one aspect which is what is your vulnerability to developing cancer? Because, you know, many of us are, you know, will have cancer cells emerging in our body every day or so we need those aspects of our immune system to prevent those cells from becoming the disease that we call cancer.

   5. PAPeter Attia37:47

      I mean, that's such an important point, and I'm probably biased because I, I trained in an immunotherapy lab, but I don't think people necessarily appreciate that we pretty much always have cancer, and our immune system is pretty much always protecting us. It's actually the exception when the cancer develops into something clinically.

   6. MWMatthew Walker38:07

      Correct. Yeah.

   7. PAPeter Attia38:07

      And, you know, I've debated-- Not debated is the wrong question. I-- One of my favorite sort of sitting around dinner discussions with, with cancer biologists is what is the greater driving force for the obvious age association of cancer? In other words, why does cancer increase nonlinearly as you age? And I offer two hypotheses. Is it-- Three, actually. Is it an increase in the rate of mutagenesis?

   8. MWMatthew Walker38:35

      Yeah.

   9. PAPeter Attia38:35

      Do you ex- do you experience on a per unit of time basis a greater insult to the genome? Two, if you assume that that's the same, is it that over time the accumulation and the expression, the phenotype of that becomes more problematic? And/or three, is it that our immune system, specifically the adaptive immune system, is weakening and w- the balance starts tipping in favor of cancer? And, you know, I've asked this question of Nobel laureates and future Nobel laureates. Every one of them has said we don't know. They suspect it's all of the above, but they all agree that the weakening of the adaptive immune system is almost assuredly playing a role in why we get cancer more as we age because we know many things are working against us when we do that. And so when I hear you say NK cells, which, you know, the CD8 cell, the NK cell, the CD4 cell, these are, these are your Green Berets and your Navy SEALs of the war against cancer. If you put a hit on those guys, you, you know, you could be taking a ten-year step in the wrong direction.

   10. MWMatthew Walker39:45

       Correct.

   11. PAPeter Attia39:46

       Just as you talked about the gonadal ten-year leap, right?

   12. MWMatthew Walker39:49

       Yeah.

   13. PAPeter Attia39:49

       With testosterone, I mean.

   14. MWMatthew Walker39:50

       I would love to add a three B hypothesis there, which is that one of the most dramatic changes with age and the most sizable and robust physiological changes in-- with age that we see is that your sleep gets worse. And sleep is probably one of the most powerful regulators of your immune system. You know, if you want a full arsenal and you want every single weapon in there to be sharp and ready to annihilate, sleep is what you need. That data I think is very clear in terms of the decimation of your immune system with sleep and that, you know, I just gave one example there too.

8. 40:31 – 43:40

   The Industrial Era and Sleep Loss as Underestimated Harm

   1. PAPeter Attia40:31

      And, and the funny thing is, like, you give that example and it's not even that dramatic. Like, there's no person listening to this who hasn't had a four-hour sleep night. That's part and parcel for just being a human being in the civilized world.

   2. MWMatthew Walker40:43

      Yeah.

   3. PAPeter Attia40:43

      Maybe even in the non-civilized world, right? And yet to think about a lifetime of stacking those things and the compounding effect of what does it mean to get eight hours a night versus six point two, two five hours a night, imagine that. I'm almost amazed it doesn't kill us quicker because to your point, we have adapted a great system to cope with excess nutrients, right? We had a great system, and it takes a long time for that to, to break us down. I think in some ways we're probably so naive in our ability to measure the short-term consequences of sleep. I mean, not you of course, because this is what you think about day and night.

   4. MWMatthew Walker41:23

      No, I think you're right. I think you're right.

   5. PAPeter Attia41:23

      But I think as a medical community, we're really shitty at knowing how to measure short term, like what's really happening in sleep deprivation.

   6. MWMatthew Walker41:32

      Especially in, you know, in clinics and in, in healthcare systems.

   7. PAPeter Attia41:35

      Yeah, like in schools.

   8. MWMatthew Walker41:36

      I think we are.

   9. PAPeter Attia41:37

      Like, we don't really understand how bad sleep deprivation is on a learning child. We don't-- we clearly don't understand what it's doing on the road. Like, we d- we don't understand that this will kill you much faster than, you know, bad nutrition.

   10. MWMatthew Walker41:51

       Right.

   11. PAPeter Attia41:51

       Which is clearly going to kill you.

   12. MWMatthew Walker41:53

       And it's an ex-- You know, if you look at all-cause mortality and short sleep, it's not even linear, it's exponential. You know, it really, it-- sleep will bend that curve of your lifespan in a downward direction with a dart into the ground when it starts to get short.

   13. PAPeter Attia42:09

       I think your argument is so great that it really comes down to the fact that At least we had a system in place to train us for excess nutrients. Now, look, we can argue we didn't have a system to train us to consume refined carbohydrates. We didn't have a system that trained to consume massive amounts of polyunsaturated fats or high, high amounts of sucrose. But we still knew how to consume some of these things, and there is a dampening effect in nutrition that the, you know, ever-present adipocyte can numb and at least for a while blunt that system. But you're right, if we didn't -- if it wasn't really until, what, probably 200 years ago that sleep deprivation could have become common, I mean, when, when do you really think was the tipping point? I know that in the '40s we could compare the '40s to today, but it would almost seem like the light bulb was a pretty big step in the wrong direction.

   14. MWMatthew Walker43:00

       The electrified-

   15. PAPeter Attia43:01

       Yeah

   16. MWMatthew Walker43:02

       ... you know, you can go back-

   17. PAPeter Attia43:02

       Not to blame Edison, but yeah

   18. MWMatthew Walker43:03

       ... yeah, but you could go back and you could argue that, you know, Edison with the light bulb and his, his company may have been the starting point. I think it's, it was probably happening even earlier on the basis of social demands. You know, the industrial era, I think then really-

   19. PAPeter Attia43:20

       Yeah, I mean, yeah

   20. MWMatthew Walker43:20

       ... starts to compound things. Once we switch from an agrarian society to an industrial society, in my mind, that's when stuff really started to go wrong.

   21. PAPeter Attia43:27

       Which is real- I mean, my history is horrible, but that's about 250 years ago, right?

   22. MWMatthew Walker43:30

       Yeah, exactly, yeah. So I think we've been, that, that curve has started to happen, um-

   23. PAPeter Attia43:34

       So it's an evolutionary millisecond.

   24. MWMatthew Walker43:36

       Correct. Correct. Sounds like a long time, a blink of an eye.

9. 43:40 – 46:36

   Sleep Loss and Tumor Growth in Mice

   1. MWMatthew Walker43:40

      The other aspect of, you know, cancer is not just that you increase your risk for developing cancer because you weaken the immune system components that are there to combat against all of those, you know, carcinogenic influences cellularly that you've just described. But another study by a colleague at the University of Chicago, David Gozal, he looks at the relationship between sleep loss and cancer in mice, and I'll just give you one example of a study he did. Took a group of mice, inoculated them with some cancer cells on their back, and then gave that cancer a one-month period to grow. At the end of the month, he resected the skin, measured the size of the tumor. Half of those mice were allowed to sleep normally. The other half had their sleep restricted. So they just had their sleep kind of top and tailed, not total deprivation, just limiting their sleep in the morning and the evening a little bit. What they found is that at the end of that one month, those underslept mice, when they looked at them, the tumor was 200% larger. I mean, it was physically distorting the body. And if you were to see these pictures, you know, you would just think, "My goodness," you know. I can see a small, tiny little sort of dot that is the growth of the, the cancer in the well-slept mice. You know, the others, it just looked like a hideous, you know, mass on these underslept mice. Secondly, what they found was that that cancer in those underslept mice had actually metastasized, which is just, you know, in some ways a fancy way of saying that it had breached the original origin and started to invade other organs, bone as well as brain. And when cancer becomes metastatic, you know, that's when we know things can get really dark and grim in terms of life expectancy.

   2. PAPeter Attia45:25

      There are many mechanisms that you could generate or s- or hypothesize-

   3. MWMatthew Walker45:29

      Positive, yeah

   4. PAPeter Attia45:30

      ... could explain that. I'm, I'm curious as to how many there were. So, so one would, I think, be exactly what we've described, which is this immune weakening.

   5. MWMatthew Walker45:36

      Yeah.

   6. PAPeter Attia45:37

      But you could also look at, so hypercortisolemia is going to drive hepatic glucose output.

   7. MWMatthew Walker45:42

      So they actually-

   8. PAPeter Attia45:42

      That's going to create hyperinsulinemia. Did they cor- when you looked at those-

   9. MWMatthew Walker45:44

      They, they adrenalectomized the mice and then they fed them-

   10. PAPeter Attia45:47

       Prior to that

   11. MWMatthew Walker45:47

       ... prior to it, so they controlled the stress-

   12. PAPeter Attia45:49

       They controlled the metabolic response?

   13. MWMatthew Walker45:51

       Correct, yeah. And what they did find in terms of -- they looked a little bit at the mechanism -- they found that macrophage M1 cells, those were actually down-regulated by a lack of sleep. And what was up-regulated was a sort of a rogue version, which was called the M2 cells, which seem to have a tumor promotion component to them as well.

   14. PAPeter Attia46:11

       Wow, so, so they really -- But the, the adrenalectomy is brilliant. What a, what a clever design.

   15. MWMatthew Walker46:16

       So you have to take out the stress response, and they limited that and yet still-

   16. PAPeter Attia46:19

       Imagine if you didn't.

   17. MWMatthew Walker46:21

       And that's the fear, is how much worse would it be when it really happens in humans because you will have that plus this huge tsunami of a cortisol impact, hypercortisol impact, which is only going to make things worse.

10. 46:36 – 57:41

    Sleep Deprivation in Medical Training

    1. PAPeter Attia46:36

       So, so, so bring this now back to the clinical tragedy here, right? Which is, again, the weakness of our profession, and I say ours meaning mine and not yours. You take a patient who's got a diagnosis of cancer. Do you think anxiety is going to go up? Hell yes, right? Do you think their sleep is going to deteriorate on no basis other than the fact that they have this diagnosis and they're often undergoing horrible treatment, right? It's amazing to me that I can't imagine how many oncologists are thinking through this problem, right? Which is as careful as we are about crafting what the chemotherapy regimen looks like, what the exact... If you go to ASCO, right, if you go to the largest oncology meeting, I don't know how many papers are being addressed on this topic. Do you?

    2. MWMatthew Walker47:18

       Yeah. No, I, and I think there are, they are few and far between with regards to sleep.

    3. PAPeter Attia47:21

       Whereas if you, if you think about some of the stuff we machinate over in oncology, like exactly who gets the sentinel node biopsy versus this, and well, what if this is an ER/PR-positive breast cancer versus an ER positive, PR negative? Or like we could, we could noodle and, and machinate on the most minute details, which, you know, maybe they matter, maybe they don't, and yet something like this seems so obvious and yet, you know, we just seem ill-equipped to deal with it. Like it, it's almost like you'd say-

    4. MWMatthew Walker47:50

       And it doesn't surprise me either, by the way. It's not your fault as a medical profession, you know, and be- being part of that profession. You know, what, what I did was I looked at a retrospective and I looked at medical curriculums across, you know, the top 20 first world countries practicing medicine. And what you find is that on average, most doctors get about one to two hours of education regarding sleep. So one to two hours regarding a third of the patients' lives.

    5. PAPeter Attia48:19

       Mm.

    6. MWMatthew Walker48:20

       That is so anemic in terms of meeting the needs. But the critical part is that one-third of their life spent sleeping also makes such a huge difference to their two-thirds of their life awake. That is just, to me, unacceptable.

    7. PAPeter Attia48:37

       And there's a deeper problem, which is in training to be a part of that profession, you enter a culture that is as difficult as the one you described where, you know, heads of state are chest-pounding about how little they sleep. I mean, I'll just pause for a moment to share another sort of set of stories. So when I started my residency, we were on call every third night. I mean, every third night, you know, I think my record, I think the most sleep I ever got on call in five years was five hours, and that happened once. And it wasn't, of course, straight five hours, but I had accumulated five hours of sleep on a call night. So I think you would average probably two to two and a half hours of sleep every third night. But that's average, so guess what? Lots of those times are 30 minutes or less. So you're on call every third night. So it's my second month on the job. So the way it works is you, you're basically either on call, post call, or pre-call. Those would be your designations. So I come in on a Monday. I am pre-call. So it's my day before my call day. So you, you know, you come in at 5:00 in the morning. You would normally leave by about 8:00 at night or 7:00 at night. And as we're finishing our rounds that evening, someone, a surgical resident, had failed to show for the ER shift. He got sick. So the chief resident said, you know, "Hey, we need somebody to stick around tonight to cover the ER." So I volunteered because I want to show how tough I am. Like, of course I can do this. So I stick around. I do the ER shift that night, and of course, in the ER, you're absolutely not... You're, you don't get one minute of sleep, obviously.

    8. MWMatthew Walker50:12

       Yeah.

    9. PAPeter Attia50:13

       Now it's Tuesday. Now I'm on call, so I'm awake, of course, all day Tuesday and Tuesday night and Wednesday, and I probably slept an hour Tuesday into Wednesday. Now it's Wednesday. I get to go home early, which means 6:00 PM on Wednesday. So I've been up since Monday morning. So this is not, like, within the realm of the type of sleep deprivation that's gonna kill you. There are lots of people in the life-

    10. MWMatthew Walker50:37

        Well, I'll come back to that.

    11. PAPeter Attia50:38

        Yeah, yeah. No, it almost did.

    12. MWMatthew Walker50:39

        Maybe, actually. Yeah, but yeah.

    13. PAPeter Attia50:40

        Okay, so I'm driving home.

    14. MWMatthew Walker50:42

        My point, in case [laughs]

    15. PAPeter Attia50:44

        Yeah. So I'm driving home. So I have quite a long drive till I have to get to the freeway. It's about two miles, but it's, like, stop signs and streetlights, and then I have to get to the freeway, and then I've got kind of a, a hike home. At the p- this point in time, I live kind of north of the hospital. I notice something really odd. Every time I come to a stoplight or stop sign, I can't keep my foot on the clutch because for some reason, I just, I have a habit of, like, keeping my foot on the clutch and keeping it in first as opposed to just sitting in neutral, which, whatever. So the point is, I keep stalling, and I'm thinking, "God, I've never done this in my life. Like, why can't I even sit here for 27 seconds and maintain my motor control over this thing?" So I'm at about the last street, maybe, maybe two streets away from before I have to get on the freeway for a 15-minute drive, and in what I can only describe as one of the best, dumbest decisions of my life, I decide, "I freaking cannot get on this freeway. I'm going to die." So I pull over to the side of this road, Eastern Avenue, and there's this park called Patterson Park. I have no idea what Patterson Park is like today, but at the time, I knew nothing about it other than it was grassy. It turned out at the time it was like, you know, a, an open-air drug market. And, and this is now speaks to the second point. So I had really good judgment, which was, "Don't get on the freeway," but then I exercise-

    16. MWMatthew Walker52:11

        Yeah. [laughs]

    17. PAPeter Attia52:11

        ... comically bad judgment-

    18. MWMatthew Walker52:13

        Yeah

    19. PAPeter Attia52:13

        ... which is, "I'm going to go take a nap in the park." So I get out of my car, probably didn't even lock it, walked into the park, put my pager on my neck of my scrubs, set the alarm for one hour. It's like 6:00 PM. Wake up at 2:00 AM in the middle of the park-

    20. MWMatthew Walker52:33

        Yeah

    21. PAPeter Attia52:34

        ... with rat bites on my arms. I mean, this is, like, the drug-infested, rat-infested park, and just think to myself, "What in the hell just happened?" I had about three of those in residency. The other thing that happened once in residency, same situation, every third night call, but I had to take an extra shift in there. And to be clear, I volunteered, right? It wasn't like, no one put a gun to my head and said, "You have to do this." I volunteered for someone who couldn't take a night of call, so I basically was on the same thing. But now I'm way further into my residency. You know, this was in my, like, fifth year of training, and I think the accumulation of that was devastating. And so now it's 2:00 in the morning on that third night, and we're operating on a patient, and the way it works in residency is when you're a senior enough resident, you're the operating surgeon, meaning you're the one doing the case. The attending surgeon is assisting you. Now, this is a very trivial operation we were doing. The only reason, in fact, we did it in the middle of the night is just to get the OR time. Like, it wasn't even an emergent case. It certainly could have waited a day. It was just removing the gallbladder laparoscopically. So I'm holding the two devices, the, and the trocars, and I'm doing the case, and the attending is just retracting for me. And I don't know how it happened, but I fell asleep on the patient and face-planted directly onto the patient. And again, the only solace you could-

    22. MWMatthew Walker54:06

        Can you imagine the amount of sleep pressure-

    23. PAPeter Attia54:10

        Yeah

    24. MWMatthew Walker54:10

        ... that was necessary to build up for you to... I mean, at that-

    25. PAPeter Attia54:14

        And I remembered that I had had a, a number of head drops prior.

    26. MWMatthew Walker54:17

        Exactly, yeah.

    27. PAPeter Attia54:18

        You know, like the, "Oh, oh."

    28. MWMatthew Walker54:18

        Yeah. Everyone's, like, jamming to good music, but no, they're not.

    29. PAPeter Attia54:21

        [laughs]

    30. MWMatthew Walker54:21

        It's just like they're falling asleep.
11. 57:41 – 1:04:54

    Reforming Residency Hours

    1. PAPeter Attia57:41

       and I wanna just, you know, have a mea culpa because there are few people that were more vocal, more vocally opposed in our residency than me when this 80-hour workweek came in, and my view was not that sleep was, you know, good and we needed more of it. I, I really didn't have a point of view on that. I actually frankly hadn't reflected on that 'cause I obviously didn't know any of the data you shared. My view was the conditions under which we work are horrible, and that's a selection feature.

    2. MWMatthew Walker58:12

       Hmm.

    3. PAPeter Attia58:12

       You want people that are willing to opt into that, who are willing to take that much pain to do this, and I had this whole thesis, which I have no idea if it turned out to be true or not, that if you lowered the bar, lowered the pain, you would bring in a broader demographic. Now, regardless of whether that's true or not, it doesn't really matter [chuckles] in the face of this data. In other words, you... If, if it is true that back in the day you were just training better physicians because you were attracting people that could persevere more or had whatever, you know, make up your thing-

    4. MWMatthew Walker58:47

       Right

    5. PAPeter Attia58:48

       ... it still doesn't change the fact you've got to come up with a new screen for that, right?

    6. MWMatthew Walker58:51

       Yeah, you can't get round that-

    7. PAPeter Attia58:51

       You've got to come up with a new filter. No

    8. MWMatthew Walker58:52

       ... evidence of the deleterious impact of even if you attract, even if it's just a selection bias that you're bringing in these hard-knuckle folks who can just jam through with wakefulness in ways that, you know, really are just horrific for everyone involved, you still can't get around the fact that they're not going to be performing medicine at its highest. And we know for a fact that you don't need to. So I think the only piece of evidence that favors that type of, you know, 30-hour continuous residency type of mentality, the only good argument I've heard is continuity of care, that once you go down to a shorter amount of time, you lose continuity of care with the patient, that you're cycling doctors between patients. But I have to say, though, even that I don't believe, because when I looked at systematically at the other medical practices, there are places that train wonderful physicians that have a maximum of somewhere between 12 to 16 hours, places like New Zealand, Sweden, and France. They all limit their junior doctors to training on nothing more than those amount of hours. And if you then look at the ranking of the medical systems in terms of how well they're doing, those guys are way up there at the top. So I find it difficult to see a case for arguing for the ability to train doctors with insufficient sleep.

    9. PAPeter Attia1:00:25

       I'll tell you what I think is going on, 'cause I agree. I mean, I, I haven't... I've been away from it for so long, but I've spoken to a few people who have kept up with the sort of medical education literature, and it turns out the 80-hour workweek has not solved the problems that they had wanted. I don't believe that medical errors have necessarily gone down. Now, you could argue, well, 80's not low enough. But I also think a, a more subtle part of it is in the countries that you mentioned, I suspect that it is the cultural norm of not just the residents, but the people who train those residents, because they were trained in that sort of more humane way-

    10. MWMatthew Walker1:00:59

        Yeah

    11. PAPeter Attia1:01:00

        ... that you bring a different way of thinking about handing off a patient. It means something different because it's just so ingrained in that's how medicine is practiced. And I think what happened in the United States, and again, this is wild speculation. I, I don't follow this literature, but just based on what I've seen since, I suspect that when you overnight created a new rule, which I think took place like July 1st, 2003, new rule, right? Overnight. But none of the people that were leading that had trained under those conditions, they didn't necessarily know how to teach under those conditions. They didn't understand, as we said, like what does it mean to hand off a patient after 16 hours?

    12. MWMatthew Walker1:01:41

        Right.

    13. PAPeter Attia1:01:42

        Because in our day, you were responsible for everything. I mean, you wouldn't dream of doing something like that because you just don't know how to communicate what needs to be done to the next person.

    14. MWMatthew Walker1:01:55

        Yeah. Yeah.

    15. PAPeter Attia1:01:55

        I mean, so much of it just comes down to that. So I suspect that's a big part of it. And of course, unfortunately, that would suggest that this is going to take time, but it still has to change.

    16. MWMatthew Walker1:02:05

        It's time, but I s- I fear it, it, that type of mentality is going to die one generation at a time because in part there was, you know, it's a bit of an old boys network, I think some of it. But you mentioned those things about how do we understand the informational transfer, the propagation from one doctor to the next regarding continuity of the patient who remains, and I think that really is an important point. Part of me, though, feels as though we've been able to put people on the moon, and that was non-trivial, but we solved it. I think we can also probably solve continuity of care and protect both patient and doctor alike in terms of their well-being-

    17. PAPeter Attia1:02:45

        Right

    18. MWMatthew Walker1:02:45

        ... and still do it. So I think it's n- I, I don't mean to-

    19. PAPeter Attia1:02:47

        No, this is cultural. No, no, no. This is-

    20. MWMatthew Walker1:02:48

        You know, I don't mean to sort of trivialize the problem, and I think what I want to try and do here is, you know, just raise my hands and say that, you know, I, I really appreciate how hard that is. It's n- it's just like early school start times and the work that I'm doing there to try and lobby for kids to start later. That's not a small thing either, because you've got to solve multiple problems. You've got to solve bus unions, bus transportation. You've got parents who need to be in work at a certain time point, and, you know, starting those times later is going to be non-trivial. All of these things are hard problems, and it's not as though I'm either ignorant of those and I want to really recognize how hard they are. But what I would also love to do is to try and just make sure that we don't lose sight of the end outcome here. The end outcome in terms of education is our children and making sure that we are not essentially educating our children amnesic by way of their insufficient sleep, and the same is true for our patients and our doctors. Let's keep the target that we have in our crosshair at the end of this process in mind rather than get perhaps distracted by how difficult the problem is. It is difficult, and I'm so sympathetic to that. I know it's hard, but there's so much on the line. There is too much on the line for us to be swayed by the difficulty of the problem in terms of the importance of the solution that we must reach.

    21. PAPeter Attia1:04:21

        No, no, no. I don't disagree with anything you've said. I think what I'm trying to do is provide an explanation for why... And it's not an excuse, more of an explanation for why I think the experiment has failed here, and it probably speaks to the need for a greater buy-in to the gravity of the problem, and therefore a greater emphasis on solving what I agree are quite, in the grand scheme of things, trivial problems. I mean, splitting the atom was hard. Putting a man on the moon, that was hard. Eradicating slavery, that was hard. All of these things have been done.

12. 1:04:54 – 1:17:49

    Early School Start Times and Teen Sleep

    1. MWMatthew Walker1:04:54

       But I think we will look back, you know, with shame, just like you were describing to your family regarding sleep and insufficient sleep as we look back now with smoking, you know, f- 50 years ago. We will look back in probably 20 years with shame that we were having schools start at 7:30 in the morning. By the way, for schools that start at 7:30 in the morning, buses will start leaving at 5:30 in the morning. That means some kids are having to wake up at 5:15, five o'clock, or even earlier, which in my mind is lunacy. And I think the shame will be present when we consider the impact, and the impact we already know from the studies there. When we delay school start times, what we see is that academic grades improve. We see truancy rates decrease. We see behavioral problems and psychiatric problems also decrease. You see the number of people who drop out of school and drop out of certain classes also decrease. And then finally, shockingly, the life expectancy of students increases, and the reason that it increases is because of car crashes. There's a great study in Teton County in Wyoming. They shifted their school start times from 7:35 in the morning to 8:55 in the morning, and then they looked to see in just this narrow age range of just 16 to 18 years old what was the change in car accidents. And what they found in that following year, not just that the kids reported getting one hour of extra sleep, there was a 70% drop in car crashes that following year. Now, the advent of ABS technology in cars, anti-lock brake systems, that dropped accident rates by 20 to 25%, and it was deemed a revolution by some people. Well, here is a biological feature, getting enough sleep, that will drop accident rates by up to 70%. So When sleep is abundant, minds will flourish, and if our goal as educators truly is to educate and not risk lives in the process, then I fear that we are failing our children in a quite spectacular manner with this incessant model of early school start times.

    2. PAPeter Attia1:07:09

       So say a little bit more on this. You and I have talked about this in the past, which is, and I think I even posed the question to you this way, which was, you know, all things equal, Matt, if you're trying to pick between three schools for your kids, like would you weigh start time in the matrix of decision? And you, you know, your answer was emphatically yes. Why is this the case? Why is it that do kids just, is there something in their brain as they're developing that it's just a question of they need more sleep and therefore you'll pick it up in the morning? Or is there something about they need to sleep to a later time that won't be solved by putting them to bed earlier?

    3. MWMatthew Walker1:07:46

       All of the above. So firstly, you know, kids, even when you're 16, 17, 18, you're still needing nine to 10 hours of sleep because your brain doesn't finish developing until it's about 25.

    4. PAPeter Attia1:08:00

       What percentage of 18-year-olds in the US do we believe are getting that sleep? Or if it's easier to answer the question, what do we believe is the median duration of sleep for an 18-year-old?

    5. MWMatthew Walker1:08:10

       About 11%.

    6. PAPeter Attia1:08:11

       11% are achieving the required, okay.

    7. MWMatthew Walker1:08:14

       89% are not getting sufficient sleep.

    8. PAPeter Attia1:08:18

       And do we have a sense of what that average is? I think the, the numbers you quoted earlier, I assume were for adults, or was that for all comers?

    9. MWMatthew Walker1:08:23

       No, that was for adults. For teenagers, it's prob- it's down to about seven hours when it should be somewhere between nine to 10 hours. So the relative-

    10. PAPeter Attia1:08:33

        So it's a bigger deficit than adults

    11. MWMatthew Walker1:08:35

        ... so the relative deficit is bigger than it is in adults. What's also striking, by the way, is if you look at parents and you ask them, "Do you think your teenager is getting sufficient sleep?" 72% of them will say, "Yes, I think my teenager is getting the sleep that they need." Yet only 11% of them are getting the necessary sleep. So in other words, there is a mismatch here between the parental and child sleep equation, and what that also leads to then, because parents believe that their kids are getting enough sleep, there is a parent to child transmission of sleep neglect. And what I mean by that is, you know, the pulling the covers off at the weekend when these kids are sleeping in for two reasons. Firstly, they're sleeping in because naturally their biological circadian rhythm moves forward in time, so they, they want to go to bed later and wake up later. It's not their choice. They don't get a choice in that.

    12. PAPeter Attia1:09:31

        So for-

    13. MWMatthew Walker1:09:32

        It's biological. It's hardwired.

    14. PAPeter Attia1:09:33

        So for a parent listening, what would you say to them if they're wrestling with their kid's sleep schedule? What do we think is the most natural time to bed, time to rise for a 16, 17, 18-year-old?

    15. MWMatthew Walker1:09:48

        I think for, you know, for 16, 17, you know, you're looking at a 10-hour period probably from, you know, somewhere between 10 to midnight, depending on their chronotype-

    16. PAPeter Attia1:09:59

        Mm-hmm

    17. MWMatthew Walker1:09:59

        ... to then sleeping in until, you know, essentially somewhere between 8:30 to 10:30 the following morning. Now, the reason that that is actually still too early though is because that would be what would naturally happen if you were to let them sleep like that every single night of the seven days of the week, but we don't, because what we do is during the five days of the school week, we are getting them up way too early. You can even put them to bed at, you know, 9:00 or 10:00 and say, "Sleep." They can't biologically, so they won't be sleeping as well during the week, so at the weekend they're trying to sleep off a chronic debt that we've saddled them with during the week due to early school start time. So no wonder they've got such a sleep pressure that is forcing them to try and sleep until, like, 1:00 or 2:00 in the afternoon. So then we chastise them for saying, "You're lazy. Get out of bed. You're wasting the day," but it's not their fault, firstly because their biological rhythms, their circadian rhythm wants them to be asleep late in- into the morning and into the early afternoon. And secondly, they've got this huge debt of sleep that they're having to rebound from in terms of sleeping, trying to sleep off that debt that the school systems have given them as well. So to me, I, I think we just need to, you know, reformulate our notion of how important sleep is in that context.

    18. PAPeter Attia1:11:26

        Now, and, and you've already alluded to this, that's a hard one to solve, right? Because you're restructuring when a parent goes to work, et cetera.

    19. MWMatthew Walker1:11:32

        It is nontrivial.

    20. PAPeter Attia1:11:34

        So what would be a middle ground that would be a great compromise? In other words, like, if a, if a school started at 9:00 AM, I feel like when I was in high school, we started at 9:00 AM.

    21. MWMatthew Walker1:11:43

        Well, ironically, yeah, what's happened is that back in the '60s, schools were starting around nine o'clock, and then ever more as we marched on in terms of our, quote-unquote, development in society in the US, that time has actually gone back and back to earlier and earlier start times, I think because it's been squeezed by the v- the sort of the vice grips of, you know, work schedules, where parents are having to work longer hours. They are ultimately commuting for longer, so they have to leave the house ever earlier, so they have to put the s- kids in school ever earlier. And I think many of these kids are just sitting there unabsorbent, like a waterlogged sponge. They're not going to be taking up information. And in fact, if you look at the data regarding delayed school start times and you ask, yes, overall GPA, SAT scores, all of them rocket up. They all improve when you delay school start times. But which classes get the biggest benefit in terms of the grade improvement? It tends to be not the classes in the afternoon where they are finally awake because of their circadian rhythm. It's the classes in the morning where before those classes would be starting at, you know, eight o'clock but now are starting at 9:30. When you push them to 9:30, they're doing much better in those classes, and it reaffirms the case that the hit that is going on in terms of the amnesic impact that early school start times are having is really in those morning hours when the brain is not designed to be awake, and it's certainly not designed to be receiving an education. It's designed to be asleep, preparing itself for its education, which should really start at maybe 9:00 or 10:00 in the morning. I mean, the United Kingdom right now, as we speak at the time of this podcast, there is a bill that's going through that will lobby for a 10:00 AM start time, which I think is probably the, the sweet spot.

    22. PAPeter Attia1:13:47

        And the reality of it is, 'cause someone will say, "Well, great, what do you want, kids to stay in school till 6:00 PM and blah, blah, blah, blah?" But m- my guess is you could probably do less with more if you did it right. In other words, you wouldn't need to spend as much time in school if you could cram-

    23. MWMatthew Walker1:14:01

        You could course correct. You could efficient- you know, more efficiently learn that information, and we've done these studies. You absolutely do learn more efficiently when you have had sufficient sleep. So it's a forcing function. Could you compress it? It's like zipping a file, you know, the amount of information that can be stored is much greater. But what's also interesting, let's say that that's not the case, and you say, "Look, to do all of this staggered system with the bus unions and to make it work out with parents and work schedules, it's gonna require more money to figure this out." Well, it turns out that some of that can be cost savings at the back end because kids get released later. There is a time during when kids get kicked out of school if they start early, which is this kind of criminal bewitching hour, which is where the kids are out of school, but the parents are not home yet from work, and when they get together sometimes for some kids bad things happen. That's where you see a lot of juvenile crime happen, which is in that sort of twilight hour between, you know, the, the 3:00 to 4:00 PM period when they're out of school to the 6:00 to 7:00 PM period where the parents are finally there and they get home. If you look at the cost of that criminal impact of activity in those hours and then you say, "If we were to start schools later, kids get out later, we'd limit the window of criminal opportunity," the cost savings comes back around and pays for itself for delayed school start times. So you just need to open up the aperture of your memory, think about the problem, and ultimately you can solve these equations.

    24. PAPeter Attia1:15:42

        My daughter hates when I say this, but I, I keep saying to her that I think this whole summer vacation thing's ridiculous because, you know, it's sort of an artifact of a, a world when you needed the kids to sort of work in the farm in the summer. But it almost seems like having a shorter day, shorter time in school, more time... In other words, uniform the situation, right? More time to do extracurricular things, more time to sleep, but just go to school 12 months out of the year. Like, go to school like we work. [chuckles]

    25. MWMatthew Walker1:16:09

        Yeah.

    26. PAPeter Attia1:16:09

        Right?

    27. MWMatthew Walker1:16:09

        Yeah.

    28. PAPeter Attia1:16:10

        That seems to be also culturally a very difficult solution, but conceptually an easier way to approach this as well.

    29. MWMatthew Walker1:16:16

        I mean, I love your idea, and I do think that the data supports it empirically right now, which is that you may not necessarily need to just simply take the school day and push it forward in time. You may just need to take the start of school and push it forward in time and hold constant the end of the day. But by way of that sufficient sleep, ultimately you may be able to still gain the same amount of intellectual equity within the minds of those young individuals by way of that sort of later school start time and greater sleep as a consequence.

    30. PAPeter Attia1:16:51

        And it also just seems like something that is so amenable to testing. I mean, it's very easy to do-
13. 1:17:49 – 1:30:10

    Screens, Light, and Teenagers' Sleep

    1. MWMatthew Walker1:17:49

       I think probably right now the best thing to do is to try and excise technology, and, you know, I'm very fearful of this.

    2. PAPeter Attia1:17:58

       When you say that, can you-- Yeah, just say that again.

    3. MWMatthew Walker1:18:00

       Yeah.

    4. PAPeter Attia1:18:00

       That is such a, I mean, that is such a, a hot topic right now, but-

    5. MWMatthew Walker1:18:05

       It is

    6. PAPeter Attia1:18:05

       ... it's h- that's another discussion I had with my daughter, which is I worry that in 20 years we will look back at the idea of 10-year-olds with iPhones as, I worry we will look at it with even a worse lens than the smoking mother.

    7. MWMatthew Walker1:18:21

       Right.

    8. PAPeter Attia1:18:21

       And that's, there's twofolds, right? There's the technology piece, which we'll talk about, and then that says nothing about the whole social piece of, you know, the influence of social media and, and stuff like that. But, so sticking to the first one, you take the technology away completely. You limit light after sundown.

    9. MWMatthew Walker1:18:38

       So there's that component, which is I think just the basic impact of light, and this is scales to not just children, it scales to adults too, that we are a dark-deprived society in this modern era, and we need darkness at l- at night to allow the release of a hormone called melatonin, and that melatonin, as it rises, it will help time the onset of your sleep. And there are great studies that have been done where if you use, let's say, an iPad for an hour before bed, firstly you get about a 50% drop in the amount of melatonin that's released. So you lose 50% of the signal of sleep timing. Worse still, that melatonin peak, even though it's lower, it's 50% lower, it will arrive three hours later at night. So it's so mistimed by the, the perverse impact of the screen. So that would be like you and I living here in California, but our melatonin release is much closer to Hawaii in terms of timing [chuckles] . That's one hou- one hour of iPad reading.

    10. PAPeter Attia1:19:46

        Is that true also, Matt, for television? Does television emit the same-

    11. MWMatthew Walker1:19:51

        No, it doesn't. So television less so, but television has another mental impact, especially if you're watching it in bed. That's not a good idea because then your brain associates your bedroom as the place of being awake and watching television, not the place of sleep, and that's a-- when you start to form those maladaptive associations, it can be a trigger of insomnia and anxiety. And typically, that's one of the recommendations that we have, that you only use the bed if you're sort of struggling with your sleep, for sleep and intimacy. That's it. But to come back to the, to kids, that's the first impact, which is that the light can disturb and disrupt their melatonin significantly. We also found in those studies, by the way, that the one hour of iPad reading before bed reduced the amount of REM sleep time. When people woke up the next day, you have them rate how refreshed by your sleep do you feel? Significantly lower rates of feeling restored and refreshed by their sleep. What was also interesting is that once you stop that iPad reading, it again had this carryover effect. It had this blast radius where they kept sleeping poorly for another two to three days after that iPad reading. The second component, though, is a mental component, and I think it's the component that may be as if not stronger than the biological component with melatonin, which is firstly that these devices, um, that kids use can cause sleep procrastination. What I mean by that is, and this is just for adults too, you can be there with your phone or your iPad, and you can be sleepy, and you could fall asleep, no problem at all. But because you got it there, you just think, "Oh, just check email one more time. Just check Facebook. Oh, let me send that tweet out. And I forgot the detergent. Let me go onto Amazon very quickly, and I'll just order that." And, and then you look up, and it's forty minutes later, and now you're forty minutes short on your sleep. Sleep procrastination is a problem. But for kids, I think the, the two bigger issues are waking up in the middle of the night. There was a survey done that demonstrated that well over 80% of teenagers admit to waking up during the night to check their phones and check social media.

    12. PAPeter Attia1:22:04

        I'm sorry, say that again. Eighty percent?

    13. MWMatthew Walker1:22:06

        Eight-zero, eight-zero during the week will wake up at least once to check their devices. So you've got this dependency that is causing this alertness spike to wake you up, and that's a habit that once it builds, is quite difficult to break. The final thing, I think even if you were to be diligent and put your phone in airplane mode, what those technologies do is cause what's called anticipatory anxiety. So I think many people have had that experience of having, like, an early morning flight, and you've got to wake up at 5:30 in the morning, and you know it. You set the alarm, but you wake up at 5:28, and you are awake like a bolt.

    14. PAPeter Attia1:22:50

        Matt, I wanna-- I'm glad you brought this up. I have noticed this for my entire life. I sometimes will play the game of can you wake up at 5:28? I'm blown away at the ability to do that.

    15. MWMatthew Walker1:23:03

        Yeah.

    16. PAPeter Attia1:23:03

        Now, you can't do it if you're really sleep deprived, at least I can't.

    17. MWMatthew Walker1:23:06

        Yeah.

    18. PAPeter Attia1:23:06

        So it's not-- I can't go to bed at 2:00 AM three nights in a row and pull it off.

    19. MWMatthew Walker1:23:10

        Yeah, you'll oversleep it if you don't have the alarm.

    20. PAPeter Attia1:23:12

        What, what is that telling us about-- It's almost like I've got a CPU with a clock in it.

    21. MWMatthew Walker1:23:16

        Correct.

    22. PAPeter Attia1:23:16

        Like, no, an actual clock.

    23. MWMatthew Walker1:23:18

        No, correct. That, that's right.

    24. PAPeter Attia1:23:19

        'Cause, 'cause you can do it to a wrong time. You can miss set the clock at the bed-

    25. MWMatthew Walker1:23:25

        Yep

    26. PAPeter Attia1:23:25

        ... by ten minutes and hit that time versus true time.

    27. MWMatthew Walker1:23:28

        Right.

    28. PAPeter Attia1:23:29

        It's crazy.

    29. MWMatthew Walker1:23:30

        And there's a great experiment that I'll tell you about. But that anticipatory anxiety, that airplane example, that's kind of like the extreme version, but a weaker version, but a chronic and I think a very maligned sort of version of it happens with our phones because most people, the first thing that they do when they wake up in the morning is swipe, and they just unlock this world of anxiety that comes flooding in through their phone, emails, texts, social media. You essentially are training your brain to anticipate that wave of anxiety every morning. And what we've discovered is that when you embed that anticipatory expectation in the morning, the amount of deep sleep that you get at night is less. You end up sleeping in a shallow state, and you don't get the same amount of deep sleep. And the greater the anxiety that there is the next morning, the greater the reduction in deep sleep that you have the night before. That's why you'll feel like you've, you've had a pretty rough night of sleep when you're waking up for that early morning flight because you've just had a poor quality of sleep. But the timing thing-- So I think to come back to, to make the point here so I don't forget, I think for kids, the best recommendation right now is technology to try and limit it. And I know that's hard because the genie feels like it's out the bottle, and it's not going back in anytime soon, and I don't want to be puritanical. I don't want to be puritanical about alcohol or caffeine, about CBD, THC. I don't want to be puritanical about kids getting the sleep or timing of the sleep that they need or can't get. But what I would say is that to try and maximize that sleep in the face of early school start times, which is what we're currently facing right now, taking that technology out the bedroom is probably the single best thing that you can try and do. The other thing that they recently found was a correlation between the use of or having social media in the bedroom and fear of missing out. Because for kids, so often, and I understand this, you know, 'cause we were both kids, you could remember that, folks were going out, you know, in the afternoon. You wanted to be there. You wanted to hang out. It was fear of missing out. It was FOMO. Well, now FOMO plays out on social media, and it plays out when you disengage from the parents. It plays out, in other words, in those twilight hours. And so there is good data now showing that fear of missing out is directly related to insufficient sleep at night in teenagers. The way that you can try to help that is to try and limit the devices that give you the ability to have FOMO in the first place. So, but in truth, I don't honestly have a good set of solutions right now for this teenage sleep problem. I think it's gonna have to be letting them sleep when biologically they naturally want to sleep. Again, you fight that biology, it's not gonna go your way. It's just not.

    30. PAPeter Attia1:26:36

        Well, Matt, that, that certainly, uh, will scare any parent senseless with respect to electronics. You know, one other question on that that my daughter actually asks me all the time, if she's reading a book in bed with a, like a nightlight, is that as harmful, A, from the standpoint of light, which is actually the question she's asking, and now B would be my question more broadly. We talked about not watching TV in bed because that's creating kind of a different purpose. Is reading in bed a bad idea and/or is the, you know, sort of natural white light that... Not natural, but, you know, the white light you get from a bulb, where does that rank on the melatonin-suppressing scale?
14. 1:30:10 – 1:36:15

    Natural Light, Hunter-Gatherer Sleep, and Biphasic Sleep

    1. PAPeter Attia1:30:10

       Has the experiment been done when, this might not even be ethical today, where subjects are given no restriction on when to sleep, how long to sleep, but they are put in a perpetually light environment?

    2. MWMatthew Walker1:30:22

       No, but the opposite... Well, uh, two-

    3. PAPeter Attia1:30:26

       I know of the opposite, yeah. I'm, I'm-

    4. MWMatthew Walker1:30:28

       The, there's two... No, there, there's one experiment that has kind of been done that is like that, and then there's the other opposite, which is... So the one experiment that's not dissimilar to that actually happened inadvertently, unfortunately, which is with, um, premature babies in the neonatal intensive care unit. What they used to do was they would just leave these fluorescent, you know, light bulbs on in the, the NICU all of the time. And at that point, even though the circadian rhythm isn't especially, you know, robust in infants, they're, you know, awake, they're asleep, they're awake, they're asleep, they still need that signal of light and dark. And what they found is that when they regularized light in the neonatal intensive care unit, in other words, when they gave back darkness at night and gave strong light during the day, firstly, the infants started to sleep better. You saw about a 50% improvement in oxygen saturation in those infants, and they put more weight on within the time period because they were sleeping more regularly. And then finally, they left the NICU somewhere between two to two and a half weeks earlier. So that's the only example I know of where you take a condition where you are put under artificial continuous light conditions, and then you do the experiment where you try to mimic more naturally what a twelve, twelve hour cycle of light dark would be, and what you see are just biological changes all for the better. That's the only experiment that I know of in the positive, which is what you're describing. The reverse experiment was done where they essentially took a group of people and they said, "You know what time do you normally go to bed?" And they said, "Normally go to bed at like, I can't get sleepy until about eleven PM, and I sleep usually about six, six and a half hours." They took that group of people, off they went to the Sierras here in America, this sort of beautiful mountain range with no electricity whatsoever, no access to artificial light. And firstly, what was dramatic was that these individuals started going to bed around nine o'clock in the evening. And this wasn't necessarily just because they didn't have anything to do. They actually rated themselves as feeling sleepier earlier. Why? Because they were getting the signal of darkness at the natural time. Secondly, they went from being, you know, ardent about the fact that they were only six-and-a-half hour sleepers, and that's all that they needed, to then sleeping a little bit more than nine hours. Now, I think this point about going to bed at nine PM is a really important one. Have you ever thought about what the term midnight actually means? [laughs] It means, it means middle of the solar cycle. It means middle of the night. Whereas now, with the perversity of the industrialized civilization, midnight, and especially now in the digital revolution, means it's maybe the last time to, you know, send a few emails. Whereas if you look at hunter-gatherer tribes whose way of life hasn't changed for thousands of years, and you ask how do they sleep, as if they are a good indicator, and we think that that's probably a good indicator of how hominids should sleep, they typically go to bed about an hour and a half to two hours after sundown, so around sort of eight thirty, nine o'clock. They usually get about seven, seven and a half hours of sleep at night, and then they have a siesta-like nap in the afternoon to make it up to around about a total of nine hours. So I think what has happened with modernity is that we have changed both the amount of sleep that we're getting, we've reduced it. We've changed the timing of sleep, so we're getting less sleep, and we're getting it at a different time, quote unquote, perhaps a wrong time of night. And finally, the nature in which we obtain our sleep has been changed. It seems as though we are designed perhaps to be sleeping biphasically, which is a long bout at night and then a siesta-like nap in the afternoon. A lot of people will ask me about this two phases of sleep thing, but in a very different sense, which was you sleep about four hours, then you wake up, you kind of have a social life, and then you go back to sleep for another four hours, and it's called the two sleeps or first sleep and second sleep, and there's a great book written on this. Now, that definitely happened sometime in human civilization. It seemed to happen around the Dickensian era. But there is nothing in our biology that suggests that we should be sleeping in that way. It seems to have been a social feature, a social pressure.

    5. PAPeter Attia1:35:24

       There was a meal that took place, a large-

    6. MWMatthew Walker1:35:26

       That's right

    7. PAPeter Attia1:35:26

       ... meal that took place between those two, sandwiched between the two four-hour sleeps, right?

    8. MWMatthew Walker1:35:30

       Correct. Yeah. Yeah, and people would, you know, they would have social activities planned. They would write. They would play music, make love. People, you know, it was a real thing, but it was not a biologically defined way of sleeping.

    9. PAPeter Attia1:35:44

       It's amazing to me because-

    10. MWMatthew Walker1:35:44

        It's not n- a natural way of sleeping

    11. PAPeter Attia1:35:46

        ... you, you'd think you'd be, I mean, I guess you could condition yourself to do anything, but to wake up after four hours of sleep under any circumstance is generally quite miserable.

    12. MWMatthew Walker1:35:54

        It's rough. It's absolutely terrible. So that happened, but I think to come back to the point, it's just that how we are sleeping in modern society is not just about sleeping less, it's about sleeping less, the timing of our sleep, and the structure of our sleep. So I think those are the things that have changed.

15. 1:36:15 – 1:46:14

    Naps, Adenosine, and Insomnia's Cortisol Pattern

    1. PAPeter Attia1:36:15

       One of the questions I get asked a lot, and I, I don't know the answer, so I, I'm hoping you do, is, one, uh, you sort of touched on it, but the efficacy of naps, and two, the notion that you should or shouldn't nap if you're having sleep issues, right? So, so on the second one, I have a slightly stronger point of view, and I hope it's not incorrect, which is in that situation, the nap is, is wrong. You want the adenosine accumulation, and you want it to draw your bedtime back earlier, right? If you're struggling, I, I would rather you push through not sleeping and then go to bed at nine o'clock. But to the first question, more broadly speaking, I can't imagine that one cycles through what you described at the outset of our discussion in a twenty-minute or a hour-long nap, right? I mean, what actually... Do you have people nap in the lab as well? You must. Yeah, what does that look like?

    2. MWMatthew Walker1:37:09

       So we've done a lot of these studies where we ask, you know, what are the benefits of napping, and we certainly do find them. We find benefits for learning and memory. We find benefits on immune function. We find benefits for things like cardiovascular health in terms of metrics of heart rate variability. We see benefits in terms of lowered systolic blood pressure. All of these things we found benefit by way of a nap. Now, when I say nap, you can ask, "What do you mean by a nap?" And we've played around with that dose, as it were, and we've done sort of-- we've tried to do a little bit of a dose response curve with some of these things, too. What we found is that you can go down as low as about 20 minutes of a nap and still see some mental benefits in terms of things like learning and memory. But typically, we do a nap that is 90 minutes because that gives the ability of the brain to go through the full 90-minute cycle so that the brain can go through all of the stages of non-REM sleep, stages one through four, and it gets the shot to get to REM sleep. And then we can ask by testing people in brain scanners sort of before and after and with cognitive tests and then with peripheral body tests, we can ask, you know, what was the, the benefit of that nap relative to a group that does exactly the same thing? They lie in bed, but we don't let them fall asleep, that they may just kind of passively watch a movie. So they're inert for the same amount of time. They're in bed. They get all of the wires on the head. We try to do it as controlled as possible with the only difference between being sleep between those two groups. So you do find benefits to, to your first point. To your second point, you're absolutely right in terms of your sleep prescription for your patients. The current recommendation is this: if you are finding it difficult to sleep at night and sleep throughout the night, the recommendation is do not nap during the day. And this helps us when we try to think about the biological mechanisms of how wake and sleep actually work. And you mentioned a chemical called adenosine. So from the moment that you and I woke up this morning, and everyone listening the moment that you woke up this morning, a chemical has been building up in your brain called adenosine. The more of it that builds up, the sleepier that you will feel. So it's the sleepiness chemical. And after about 16 hours of accumulation, you should have enough weight of healthy sleepiness, you should have enough adenosine within the brain to have you fall asleep easily and then stay asleep soundly. And then when you're in sleep, the brain actually will clear away that adenosine, removing the sleepiness, and after about eight hours of sleep, you've removed 16 hours of accumulation of adenosine so that when you wake up th- in the morning, you feel alert, you feel more awake, and that's the reason that you don't feel as sleepy anymore throughout that following day. Now, the problem with naps is that if you nap in during the day, particularly if you nap in the late afternoon, essentially what you're doing there is acting like a pressure valve on a steam cooker, that you're building up all of this great, healthy sleepiness, this sleep pressure, and then you nap and shoo, you'll just release some of that sleepiness. So now when it comes to your normal bedtime, you don't feel as sleepy. Why? Because the nap removed some of that sleepiness pressure, it removed some of the adenosine, and you are going to perhaps find it more difficult to fall asleep and stay asleep. Perhaps is the important point. There are some people who can nap. If you can nap regularly and/or you don't have problems with sleep at night, then naps are just fine. But if you can't nap regularly, and especially if you're struggling with sleep at night, the advice is don't nap, stay awake, build that healthy sleepiness, build lots of adenosine. That gives you the best chance to stay asleep and then fall under the spell of sleep, under that weight of sleepiness for as long as possible.

    3. PAPeter Attia1:41:24

       You know, it might be oversimplifying, but the way I generally describe sleep to patients is sort of a balancing act between adenosine, cortisol, and melatonin. And you've got to, like, these three things have to make-- They're like an orchestra. You have to have the crescendo of adenosine with the decrescendo of cortisol, and then you have to let melatonin take the brakes off this whole thing. And, you know, even when I just think about myself personally, I am convinced that virtually all of my sleep woes are on the cortisol axis. And the reason I'm hypothesizing that is I can't measure adenosine. Uh, it's very complicated to measure.

    4. MWMatthew Walker1:42:02

       It is.

    5. PAPeter Attia1:42:03

       You need a very special type of mass spec to do that or MRS. But we can measure melatonin in urine. We can collect urine overnight and measure melatonin levels, so we have at least some sense of how much we're making. But because I measure glucose 24 hours a day and I'm pretty familiar with meal timing and response, in many ways, nighttime glucose for me is a proxy for nighttime cortisol. And the association between high nighttime glucose and poor sleep is overwhelming. And I suspect it's that-- I suspect it's through this cortisol axis.

    6. MWMatthew Walker1:42:38

       There is, in some ways, a manipulation that we'll speak about in just probably a little while of adenosine. Even though you can't measure it, you can actually manipulate it with something called caffeine, and that can demonstrate to you how-

    7. PAPeter Attia1:42:52

       Matt, by the way, we're, uh, we're in America here.

    8. MWMatthew Walker1:42:54

       [laughs]

    9. PAPeter Attia1:42:54

       I don't think there's a human that doesn't know what caffeine is. You get everybody's ears perked up like you're gonna mention, like, some new compound you just discovered in the lab yesterday.

    10. MWMatthew Walker1:43:04

        [laughs]

    11. PAPeter Attia1:43:05

        And it's like, it's, it's ca- Yeah. [laughs]

    12. MWMatthew Walker1:43:06

        Yeah, yeah. S- Somnus squared. No, no, it's called caffeine.

    13. PAPeter Attia1:43:10

        [laughs]

    14. MWMatthew Walker1:43:11

        Um, but what's interesting regarding cortisol, which really supports your hypothesis, right now, the leading underlying mechanism, the leading theory of insomnia essentially comes back to that fight or flight branch of the nervous system, that you are in this profound parasympathetic state where that nervous system is cranked too far. In sort of the high strength direction. And if you essentially have a cannula and you sample cortisol every 30 minutes across a 24-hour period, you see this, you know, this nice rise during the day where cortisol is helping you stay awake, it's keeping you alert, it's doing all of the things that it needs to do. And then as you start to come towards the nighttime period, cortisol should drop and needs to drop for you to be able to initiate sleep. And in fact, it usually hits its sort of almost its nadir at the point where most people will say, "That's my typical bedtime." And it then goes through this awesome sort of downstroke in terms of concentration, and then a few hours before you wake up, cortisol will start to rise. In other words, it's a preparatory hormone that starts to get you ready for wakefulness. If you look at patients with insomnia, however, what you see is that their cortisol starts to come down nicely in the evening, sort of 6 or 7 or 8, so, you know, they could feel just as sleepy as a regular person. But then right before bed, it goes back in the opposite direction. It spikes again and then starts to come down, and then often in the middle of the night you will see cortisol spike back again when it should be lower still before it starts its rise. Those two cortisol spikes, I think, are the natural biological bookmarks for what we call sleep onset insomnia and sleep maintenance insomnia. So your cortisol spikes just before bed, you can't fall asleep, sleep onset insomnia. Cortisol spikes in the middle of the night, you wake up, Rolodex of anxiety and brain starts to happen. Cortisol spikes, you can't fall back asleep. That's what we call sleep maintenance insomnia. Those are the two principal types of insomnia. I think that's where you can see part of the biological basis, and my guess is that if we were to measure, you know, things like your heart rate variability and we were to decompose them with some mathematical equations that you would know of, s- things like a fast Fourier transform, you can look at the contribution of the sympathetic versus parasympathetic when you break down the heart rate variability. My guess is that you're going to see that sympathetic, that fight or flight branch of the nervous system getting jacked just before sleep onset and then once again spiking in the middle of the night, underlying the cortisol spike, which underlies the awakening, which underlies the syndrome of insomnia.

16. 1:46:14 – 1:53:37

    Behavioral Treatments: Meditation and Phosphatidylserine

    1. PAPeter Attia1:46:14

       Yeah. Who do you think in that equation -- I mean, I don't want to give everyone a, a, a lecture on this topic because you've done a great job explaining what sympathetic is, right? Which is autonomic, but it's sort of different from the glucocorticoid-regulated pathway. Do you think that the sympathetic is driving the glucocorticoid or the other way around? And the only reason I ask is, in a moment, I'm gonna propose the only two things that I've ever really thought I have in the toolkit to treat that. But, but the answer to this question might impact that as well.

    2. MWMatthew Walker1:46:48

       I honestly don't think we have the evidence to argue which way round that chain of command unfolds. I just genuinely don't know of the evidence. I think both are tenable hypotheses. Both could be independent, so they, I think they could be non-mutually exclusive. So in truth, I don't think I know the evidence in favor. But what's nice is that the fact that we know that they both happen and can be causal contributors means that we've got at least two treatment targets that we can go aver- after, which I think will then play into exactly what you're going to say, which-

    3. PAPeter Attia1:47:23

       Well, I, I don't know that they're correct, but to me, when we see that pattern, because we do measure, uh, nighttime cortisol and we, you know, we measure the metabolites of it and all of these other complicated assays, when we see that high nighttime cortisol, we basically s- you know, I mean, we sort of-- That's a very hard problem to treat from an end-- You know, 'cause if you really think about it, we're just dealing with the endocrine system, right?

    4. MWMatthew Walker1:47:45

       Yeah.

    5. PAPeter Attia1:47:45

       You know, it's a heck of a lot easier to treat thyroid dysfunction and dysfunction of the sex hormones, and I'm not saying that those things are easy, but they are easier than treating the upper end of the... Like, when, when you have low sympathetic function and low glu- glucocorticoid function, that's actually easier to treat than the opposite. The hardest problem, I think, in clinical medicine from an endocrine perspective is high sympathetic output, high glucocorticoid output, and really it's amenable to behavioral therapy, right? It really comes down to a change in mindset and a change in routine. We were talking about this earlier. It's like the further I can separate bed from email, the better. Because for me, email's just, I hate email so much, so anytime I'm looking at email-

    6. MWMatthew Walker1:48:29

       Everyone else's agenda for your time.

    7. PAPeter Attia1:48:30

       Yeah, yeah, yeah. I'm just, I'm just, I have a low level of pissed off-edness whenever I'm looking at email. So the further I can separate my pissed off-edness from bed, the less my cortisol is.

    8. MWMatthew Walker1:48:41

       Can I get that T-shirt, by the way? [laughs]

    9. PAPeter Attia1:48:43

       Yeah, yeah, yeah, yeah, yeah. And then the second thing which appears to work anecdotally is phosphatidylserine at a high enough dose, which generally requires about four hundred to six hundred milligrams. And-

    10. MWMatthew Walker1:48:54

        Okay.

    11. PAPeter Attia1:48:55

        And again, for me, the only time I find that that's nec- that's really necessary is under those jet lag circumstances, you know, when you're trying to put yourself in the time zone of London when you're leaving San Francisco, and you basically have to make yourself go to bed and it's only 2:00 PM in your brain, but it's late enough there. You know, the, the phos- you know, slamming yourself with six hundred of phosphatidylserine really seems to move the needle, both in terms of your glucose response and your cortisol response. What else do you have up your sleeve on that particular problem? 'Cause I, honestly, I can't think of a more difficult clinical problem than the one you've just described.

    12. MWMatthew Walker1:49:30

        I think the glucocorticoid issue is, I think, is a really tough nut to crack. I think for the sympathetic drive- I do think you're correct that it's behavioral. There I would actually argue meditation. And I looked at this data when I was researching the book, gosh, this must have been about four years ago now. You know, and I'm, I think I'm a bit of a hard-nosed, dyed-in-the-wool scientist, so some of the... When I was reading the studies on meditation and insomnia, I was wondering if it was a bit woo-woo and didn't know how to take it seriously. But the data was very compelling in terms of it really does decrease the amount of time it takes someone to fall asleep. The continuity of their sleep is improved. If you look at some of these apps that do it very well and, you know, things like Headspace or Calm, my guess, although I don't know if they've ever released this data, is that if you were to look at their usage statistics, you will already see that people are self-medicating their insomnia by way of meditating right before bed. And I think, you know, both of those apps are starting to now launch, you know, aspects of sleep and sleep health in their portfolio of offerings, rightly so, because they've probably realized that sleep is a huge part of the issue for which people are coming to them to solve. And the clinical data is very supportive of that. So I would say that for driving, it's, it's almost impossible to fall asleep if your autonomic nervous system is pushed in a sympathetic dominant state, in a fight or flight state. And a good example of this is, you know, when you are jet lagged, you can be there, you c- you may not have slept on the plane. You can feel that you're tired, you're really tired, but for some reason, you know, your cortisol is now spiking because you're mismatched with your circadian rhythm. You can feel your heart rate, and you can just know that your nervous system is cranked, and you are tired as tired can be in your eyes and in your mind, but your nervous system, because it's on, on that sort of upward swing, will not let you fall asleep. But meditation, I think, is a great way to drive a parasympathetic dominance of the nervous system, which is to take you out of the fight or flight branch and more into this quiet, sort of more introspective state. I think that's probably the, the better thing. Now, I know it's not, from a clinical medical perspective, as desirable because it's not a pill that we can take. It's not a dosage. It's, you just have to put in the work to sit there and meditate.

    13. PAPeter Attia1:52:23

        But I think that's the nature of sleep. I mean, I think CBTI has efficacy, but it requires work.

    14. MWMatthew Walker1:52:28

        It does.

    15. PAPeter Attia1:52:29

        And changing the way you eat requires work. It's not a pill. I mean, I-

    16. MWMatthew Walker1:52:32

        And exercising, you know-

    17. PAPeter Attia1:52:33

        Yeah

    18. MWMatthew Walker1:52:33

        ... same thing.

    19. PAPeter Attia1:52:34

        And I've been asked, this is a totally unrelated topic, but people always say, "Oh my God, you know, please write me a prescription for metformin because it's going to help me lose weight," and blah, blah, blah. And I said, "Look, let me be clear. I mean, I think metformin is a really powerful pill. I don't think it's nearly as powerful as an exceptional diet." In other words, metformin superimposed on the world's worst nutrition versus no metformin on exceptional nutrition, I don't think it's any comparison. In the end, molecules that you take intermittently aren't really nearly as potent as molecular changes that occur over a time course behaviorally. I mean, that's, I mean, I, I wish that weren't true, truthfully. [laughs]

    20. MWMatthew Walker1:53:16

        Yeah, me too.

    21. PAPeter Attia1:53:16

        I, I really, I wish-

    22. MWMatthew Walker1:53:17

        I'm not anti-pharmacology-

    23. PAPeter Attia1:53:18

        Yeah, yeah

    24. MWMatthew Walker1:53:18

        ... by any means. You know, if we had a good sleeping pill, I would embrace it and I would recommend it. But right now, the sleeping pills on the markets, they firstly don't produce naturalistic sleep. Secondly, they've been associated with a significantly higher risk of death and also significantly higher risk of cancer.

17. 1:53:37 – 2:04:28

    Sleeping Pills, Ambien, and Brain Plasticity

    1. PAPeter Attia1:53:37

       I'm glad you mentioned this because this is a great segue to this topic. And, and going back to my friend Kirk Parsley, another, I remember another thing he said, 'cause I... This is g- again, going back to 2011, 2012, my go-to travel drug was Ambien. You know, fortunately, I've never, I've never had insomnia, but I empathize greatly with those who do. I've seen enough people with it. But when I needed to sleep, I was gonna take Ambien. And I remember getting hints that this wasn't a great drug when I would... When I worked at McKinsey, I used to have to go from San Francisco to Atlanta every single Monday for a day. And because I was ruthless in my pursuit of not wasting time, rather than, like, take a Sunday afternoon flight and come back Tuesday, I took a red-eye from San Francisco to Atlanta every single Sunday. And as one of my friends put it, "That's the pink eye. It ain't the red-eye." Like, that's a four-hour flight, right?

    2. MWMatthew Walker1:54:33

       [laughs]

    3. PAPeter Attia1:54:33

       You always get the tailwind.

    4. MWMatthew Walker1:54:35

       Yeah.

    5. PAPeter Attia1:54:35

       So you, you get about three and a half hours of sleep on a plane. I'd get to Atlanta at 5:00, pick up a rental car, drive to the gym, do a two-hour workout, shave, shower, get to the client, stay there all day, you know, leave at 6:30, get to the airport by, you know, 8:30, get the flight back to San Francisco. You're back by whatever. You're home at midnight. So it was a 26-hour door-to-door every single time, and I was using Ambien to make sure I slept on that flight. I would, I would come up with these grisly discoveries, which is I'd find emails I sent that I didn't know I'd sent, and thank God none of them were inappropriate. But you hear these stories of people doing really crazy stuff on Ambien.

    6. MWMatthew Walker1:55:21

       Which is never committed to memory. And, you know, it's only when people make the phone call the next morning and they say, "You know, what were you, what were you going on about last night?"

    7. PAPeter Attia1:55:30

       Oh, I-

    8. MWMatthew Walker1:55:31

       And you will say, "I don't know."

    9. PAPeter Attia1:55:31

       One of the scariest things I ever saw was I remember looking at my phone and seeing outgoing calls to people that I didn't remember making. So my friend Kirk Parsley is saying, "And by the way, that Ambien crap that you take, you know, a couple times a month," he said, "You know that's not sleep, right?" And I said, "What do you mean it's not sleep? I'm out." And he just, you know, again, you'll laugh at this because this is exactly the kind of story that you tell so eloquently. He said, "You're confusing consciousness and sleep or lack of consciousness and sleep. If I took a baseball bat and hit you on the head, I could render you completely unconscious laying on the floor for eight hours. Do you think in any way that mimics the restorative process of sleep?" I mean, not even close, right? So, you know, think of Ambien more as a chemical baseball bat to the head than something that's actually promoting what you've just been speaking about for the last, you know, little while.

    10. MWMatthew Walker1:56:26

        It's such a critical point. Again, I'm not anti-pharmacology, and I know some of the people in the drug industries, the scientists, and their goal, their passion is to create drugs that better humanity, and they are genuine and authentic about that, and I love that about them. But I also will not accept or speak in public about a drug that clearly doesn't seem to be beneficial for a certain process. And unfortunately, if you look at the evidence, firstly, you find absolutely that those drugs are a class of drugs that we call the, the things like Ambien, Lunesta, sort of, you know, all of these things that you've heard. They're a class of drugs that we call the sedative hypnotics, and sedation is not sleep, but people mistake the former with the latter, and it's not. It's literally just knocking your cortex out. So I'm not going to argue when you take those drugs that you're awake. You're clearly not awake. [chuckles] But to say that you're in naturalistic sleep is an equal fallacy because if I look at the electrical signature of your sleep when you are on or off Ambien, radically different for a start. You don't get into the same depth of deep sleep that you get. It's not the same electrical quality of deep sleep. The second thing that we found is that there does seem to be a higher association with mortality risk. Now, we don't know if it's causal, and my guess is that on the strength of the evidence right now, IRB committees, ethics committees that sort of allow you to do certain scientific studies may not even allow you to try and do those studies because the evidence is already so deleterious. The other f- finding was this strong association with risk of all forms of cancer, which perplexed me because you would think, "Well, if I'm taking this drug that helps me sleep more and sleep is so good for the immune system, including things like natural killer cells and combating sleep, then this drug-induced sleep should actually make my cancer risk lower, not higher." And the fact that it is higher, I think, tells you that the type of sleep that you're getting is not of this rich, complex, restorative, restful, biologically appropriate sleep. The other thing I would come onto, and these are very difficult studies to get funding for because, you know, obviously some of the drug companies, they may not necessarily want some of this information out there. It was the only chapter in the book, by the way, that my publisher brought in a legal team to kind of look at when I was kind of making all of these claims. But this is just, I'm just conveying the science. There's nothing controversial about the science, and they ended up feeling legally comfortable with what I wrote. There was this stunning study done by a good friend of mine called Marcus Frank at Penn, and he was looking at basically brain plasticity. How does the brain make connections and strengthen those connections? And those strengthening of connections is the underlying mechanism that we know leads to the long-term formation of memories. And it's a very well understood mechanism, this idea of brain plasticity. And there is a model where if you kind of patch the eye of an animal and then you measure the visual cortex, what you see is that once you patch one eye, the brain says, "Well, we're not going to waste the real estate of that one eye that's no longer doing visual processing. We're going to shift a lot of that over to the other eye's territory and give it even more kind of rich connective fidelity, as it were." So you've got this model of what's called monocular deprivation plasticity, which is a classic model of how the brain rewires itself for things like learning and memory. What he found is that he took a group of, um, animals and he gave them naturalistic sleep and did this kind of monocular deprivation. And sleep, it turns out, basically doubles the strengthening of plasticity. Sleep is wonderful for shifting things and making new connections and really strengthening those neural connections. Sleep is essential for brain plasticity. And it's almost, it's sleep will almost double the strength of the connections relative to if you just keep the animal awake. So sleep, it's not just time that helps the brain rewire itself. It's time with sleep that makes the difference. Then he dosed those animals with Ambien. Now firstly, the animals slept longer because they were dosed with this sedative hypnotic, and you would think that surely that should improve the strengthening of, of rewiring in the brain. It did exactly the opposite.

    11. PAPeter Attia2:01:18

        Yeah, I was gonna say, or at worse-

    12. MWMatthew Walker2:01:20

        It would make no difference

    13. PAPeter Attia2:01:21

        ... not change from the control.

    14. MWMatthew Walker2:01:22

        Right, from the control. If it was, quote-unquote, "naturalistic sleep," what he found was actually a fifty percent unwiring of the connections that had been laid down before when the animal was awake. In other words, not only had sleep failed to strengthen the connections, the Ambien-laced or the Ambien-induced sleep was doing the opposite. It was weakening connections within the brains. Now, what makes me fearful about that is firstly, if you look at the number of people who are using these medications You know, it took George Lucas, I often say, I think about 40 years with the Star Wars franchise to amass about $4 billion in profit. It took Ambien less than 24 months to amass that in terms of profit. So you've got to imagine the number of prescriptions being written are high. Then the fact that the prescription age of these sleep aids is starting to decrease gradually as parents get more concerned about their kids who may have more anxiety, who are having sleep problems, they're turning to pills. And when you bring that experiment back into the context of pediatric prescriptions of sleep medication, you've got a brain that is developing, a brain that needs to wire itself up, strengthen connections, build and mature. It needs to learn. It needs to consolidate. And then you're providing a form of sleep through medication that may actually be unwiring that nervous system and unwiring those memories rather than strengthening them. That frightens me. That frightens me.

    15. PAPeter Attia2:03:05

        You can find all of this information and more at peterattiamd.com forward slash podcast. There you'll find the show notes, readings, and links related to this episode. You can also find my blog at peterattiamd.com. Maybe the simplest thing to do is to sign up for my subjectively non-lame once-a-week email where I'll update you on what I've been up to, the most interesting papers I've read, and all things related to longevity, science, performance, sleep, etc. On social, you can find me on Twitter, Instagram, and Facebook, all with the ID peterattiamd. But usually Twitter is the best way to reach me to share your questions and comments. Now for the obligatory disclaimer. This podcast is for general informational purposes only and does not constitute the practice of medicine, nursing, or other professional healthcare services, including the giving of medical advice. And note, no doctor-patient relationship is formed. The use of this information and the materials linked to the podcast is at the user's own risk. The content of this podcast is not intended to be a substitute for professional medical advice, diagnoses, or treatment. Users should not disregard or delay in obtaining medical advice for any medical condition they have and should seek the assistance of their healthcare professionals for any such conditions. Lastly, and perhaps most importantly, I take conflicts of interest very seriously. For all of my disclosures, the companies I invest in and or advise, please visit peterattiamd.com forward slash about.

Episode duration: 2:04:31