The secrets of good sleep | Professor Matt Walker

welcome to Zoe science and nutrition we are world-leading scientists explaining how your research can improve your health we all know how

good

it feels to fall into a deep

sleep

to explore the land of dreams take stock of the day's experiences and wake up refreshed The positive The effects of a

good

night's

sleep

extend to all aspects of our lives, we feel focused, energetic and ready to take on the challenges of the day, but the long-term effects of bad sleep are less known and turn out to have a big impact on our health and even how long we live, Alzheimer's, cancer, obesity and diabetes are linked to lack of sleep, so what does the latest science tell us about how we can improve our sleep for more energy and better health?

Is it true that the way we sleep changes the way we sleep? The body responds to food to find out that we are joined by sleep expert Matthew Walker,

professor

of neuroscience at UC Berkeley and founder of the Center for the Science of Human Sleep. Matt and his team are currently working with Zoe scientists to investigate the link between sleep nutrition and health. The first scientific paper from our work together has just been published by Nature Communications and explains why you feel energized or tired when you wake up. You can find the link in our show notes.

Matt's best-selling book, Why We Sleep, transformed my own attitude toward sleep. Years later, I still follow much of his advice. I hope you find Matt's practical advice as powerful as I do. Thank you for joining me today. I really enjoyed your book. Do you know why we sleep? I read it for the first time a few years ago. first came out and I have to admit I'm not sure I told you this before, but I drove my wife crazy by turning our room into a cave afterwards so she definitely knows who you are even though she probably hasn't met you yet. for all the wrong reasons, but at least I anoint you as an ambassador of the dream for what you've been doing, Jonathan, well, thank you.

I think, as always, it's a bit like with Zoe and nutrition. You know, now I understand her so much about it and eventually she gets into it and then she becomes more obsessive than me, so she's on that path with sleep, but anyway look, it's great to have you here talking about sleep, so much your research as I think we're also going to touch on some of the research. what you're working on together with Zoe now we have kind of a tradition here on the podcast, we always like to start with a quick round of questions from our listeners and the rules are really simple, you can say yes, no or one. answer prayer, but no more, and we know scientists always find this a challenge, so are you ready for it to begin?

I'm up for the challenge, so first question, can bad sleep kill? Yes, in multiple different ways through multiple different diseases. I know. Let's talk more about that, okay, is exercising more important than sleeping well? I would say that sleep is the foundation on which exercise and nutrition are based, it is not a third pillar, it is the foundation of those other two things and I am guessing that the people who listen to this call wake up at five in the morning to exercise and we'll talk a little bit about whether it's a good idea. I mean, we will.

It's okay, it's a short nap during the day. Okay, mostly, yes. I suffer from insomnia. No, what we eat can affect how we sleep. Yes, I have a small child. Matt. They wake me up at night. Is my health doomed? No, just sleep when you can during the day or night during that time period. owned by a child, okay, that's great advice that's also sometimes hard to follow, so Matt, what's the biggest myth about sleep? Most people still believe there are so many myths, but I think one of the fun myths that has been busted is the myth of counting.

Sheep will help you fall asleep and there is a great study done here at UC Berkeley and it was not done by me but by a colleague of mine and what they found is that counting sheep not only didn't make you fall asleep faster. It actually took you longer to fall asleep when you were counting sheep, but what they did find was something interesting: there is an alternative mental strategy; That strategy is to go on a mental walk, so think about a walk that you know very well, maybe it's a walk in the woods or in the woods or a hike or a walk on the beach and then try to really visualize that to the point This is me walking out the front door, I'm walking down the stairs and I go and if you do it in granular detail and move through it, the next thing you know the alarm goes off the next morning because you've fallen asleep and It seems to be a pretty effective tool, so that's one of the many myths we can bust regarding sleep.

Great, thanks Matt and look, why don't we start from the beginning about what sleep is? I know that sounds like kind of a crazy question, because we all sleep. I think it remains one of the most mysterious questions. Key activities that happen in a human being, so could you start with us? Yes, it's very strange, isn't it? I mean, you know, we close our eyes and then we think that we essentially lose Consciousness and that our body just lies. asleep and then seven to nine hours later we wake up now that's very understandable and if I didn't know what I know about sleep I would think the same thing and as a consequence maybe I would say well look what's the problem with wasting 30 minutes or an hour here or you know , or just go down to six hours because I'm a busy person or five and a half hours because I'm actually missing out on my body getting some rest and my mind isn't really working.

Nothing could be further from the truth than the fact that your brain is incredibly active during the stages of sleep, in fact, during some stages it is up to 30 percent more active than when you are awake, more than 30 percent more active than when you are awake. when I am not. that's crazy yeah in some parts of your brain there's 30 more activity in some stages of sleep than when you're awake and then down in your body there's a radical overhaul it's like hitting the reset button on your wifi router -Fi. but it only takes seven to nine hours to do it and let me take a step back because I haven't really answered your question: what is sleep?

Sleep in human beings. In fact, in all mammal species it is divided into two main types. On the one hand, we have something called non-rapid eye movement sleep, non-rem sleep, on the other hand, we have rapid eye movement sleep or REM sleep, and REM sleep is the main stage in which we dream, now it turns out that sleep no rem is more advanced. subdivided into four separate substages which they unimaginatively called stages one through four increasing in depth, so stages three and four, that's the deep sleep we discussed, and then stages one and two of no rem, which is light, not sorry, it's light, uh, sleepy, so you might be I've seen this on some of your sleep trackers where it says that if you were awake in light sleep, in deep sleep, or in REM sleep, now those two types of non-rem sleep and RAM will end up developing into a battle for dominance of the brain throughout the night and that brain sleep.

The war will be won and lost every 90 minutes and then repeated every 90 minutes, creating the standard cyclical architecture of human sleep of 90 minutes on average in most people. What's interesting, though, is that the balance, the kind of distribution of non-Rem and REM cocktails within those 90-minute cycles changes as you go through the night. What I mean by this is that in the first half of the night, most of those 90-minute cycles are made up of a lot of deep non-rem sleep and very little REM. you sleep, but when you move into the second half of the night, that changes and instead you get a lot more REM sleep and very little deep sleep and Matt, what's all this for?

I mean, we're definitely going to imagine that's a lot. more complex than I guess, uh, most of us imagine, which is what I always felt like, oh, you go to sleep, you wake up, it's a little annoying, like all those hours when you could do something better. I think you're starting to paint this picture. Very complex, why does all this happen? learning emotional memory brain regulation brain plasticity down and in the body and overhaul of your cardiovascular system a replenishment of your immune system a reregulation of all your hormonal systems in fact 50 years ago We used to ask ourselves why we sleep and the rude answer at the time was that we sleep to cure drowsiness, which says nothing about the meaning of sleep.

Now, 50 years later, we have had to change the question to now. I have to ask if there is any major operation on your brain or is there any major physiological system in your body that does not improve wonderfully when you sleep or that demonstrably deteriorates when you do not sleep? enough and so far the answer seems to be no. that's amazing and so how does that relate to what you're describing these different stages? Are they linked to particular elements of how sleep creates all of these benefits for us? So what we've learned is that all of those stages, even some of the light forms of non-rem sleep, all of those stages of sleep are important, and that's why sometimes people come up to me and ask me how do I get a dream? deeper or how do I get more REM sleep and my The question they're often asked is why do they want to get more REM sleep or deep sleep and they'll say, "Well, isn't that a good thing?" and it turns out that it's all good. , it's just that different stages of sleep will do different things for everyone. your brain and your body at different times of the night and we can't let the brain down at any of those stages without some kind of detrimental impairment, so you need all these different stages that you're describing because each of them are doing different things. for both our mind and the rest of our body is that what you are saying is correct and when you think about it from an evolutionary perspective, of course, that must be the case because when we are asleep, sleep is the most idiotic thing of all. inventions that you know because when you are asleep you don't find a mate, you don't find food, you don't reproduce, you don't take care of your young and, even worse, you are vulnerable to predation, yes, I know.

I hadn't really given it much thought, but you're right, of course, being asleep is a terrible place to be, isn't it? Matt, do we understand what happens in this REM stage? REM sleep is associated with dreaming, but Dreaming may simply be an Epi phenomenon. You could imagine that dreaming is like a light bulb. The reason we created the light bulb apparatus is to create light, but it turns out that when you produce light that way you also produce heat. It was never like this. The reason for the light bulb is simply what happens when you produce light that way and the same could be true for dreaming that the reason the brain created this thing called REM sleep was to fulfill many different functions, but when you create REM you sleep from the way we do it, you also get this byproduct called Dreaming, it's just an Epi phenomenon.

Well, now we know that REM sleep and dreams themselves are functional. The things we have discovered are at least twofold. The first is that REM sleep. It provides a form of nighttime therapy, it is emotional first aid and it is during sleep and the particular brain chemistry of sleep where we reactivate experiences and emotional events that we have had during the day or even in the last years or months and we reprocess that information and in doing so, it's almost as if REM sleep is a nighttime calming bomb that eliminates those difficult and painful experiences so that you wake up the next day and feel better about them;

In other words, now is not the time to do it. It heals all the wounds, but it's the moment during sleep that provides emotional convalescence, that's amazing, so this idea that you know, if I sleep on this, I might feel better in the morning, I think my mother used to always tell me, you know, go. to sleep you will feel better in the morning right, you are saying that was real science, that is extraordinary, yes, and in fact there is a wonderful quote from the American businessman Joseph Kossman, who once said that the best bridge between despair and Hope it's a good night. of sleep that is exactly what we found, so that is one function of dreaming in REM sleep, the second function however relates to your learning and memory abilities and what we found is that deep non-restorative sleep is the stage of sleep in which we essentially consolidate new memories. in the brain it's like hitting the save button on that document, but when we do that, all the information we've been learning is during deep sleep and it takes a little bit longer than hitting the save button, but what does REM sleep do? ?

So, well, it turns out that REM sleep is a form of quasi-informational alchemy in which REM sleep takes all the information you've recently learned and starts tocollide and interconnect it with your entire catalog of past experiences and create new and novel links and associations so that you wake up the next morning with a revised mental network of associations that is now capable of guessing solutions to problems that were previously impenetrable, so This is the kind of Eureka moment where you wake up the next day and suddenly I know everything makes sense, even though yesterday you knew you couldn't find the solution to any problem, that's exactly what I mean, think about it, no one has ever told you.

Never said, Jonathan, you should really stay awake when faced with a problem. You know, instead they tell you to sleep, it's not a problem, it's amazing and I think we're going to talk a little bit more about the impact of good and bad sleep right before we get out of this topic because I think I can continue asking you questions about exactly how sleep works forever, but how do you solve this in your lab, do you know how you really understand what's going on? Since you know this is very different from a lot of the topics we look at at Zoe, where you know you're constantly measuring blood, for example, you can see the changes, but how do we get this kind of deep insights that you're talking about?

We use a wide range of different technologies at my sleep center here at UC Berkeley, so we'll measure your sleep with what's called high-density EEG, which means, "I'm going to put hundreds of electrodes all over your head, You look like the spaghetti monster and that allows us to pick up on all the special brain waves that occur during different stages of sleep and you have to shave my hair to do that or am I allowed to keep that up with Matt, you'd think, but no, luckily that's good that's an easy thing to do so I'm registered yeah so yeah don't worry you'll keep your um wonderful her and then we also use a wide variety of other technologies we use MRI particularly.

To look deep into the brain and observe the patterns of brain activity that change when you are entering and exiting different stages of sleep, how your brain has changed before and after a night of sleep we use special pet scanners in much of our work. , which I think we'll discuss aging and dementia to look at different pathologies of Alzheimer's disease that build up due to lack of sleep and then we use a lot of the peripheral markers that you've been describing we measure the blood, so we look many inflammatory factors, for example, in the blood, we also measure other aspects, we measure your cardiovascular system, we measure the hormonal systems, we also measure your thermoregulatory system and at this stage, there are probably almost no major systems within your body that We're not really measuring it in the lab, so I think one of the things you're really passionate about is what happens when people don't get enough sleep, Matt, yeah.

Can you talk a little bit about this because I think we live in this world where, because of electric lights and digital devices, we are no longer left without anything interesting to do after dark and so you probably know clearly that we just You sleep while As much as our body wants, most of us have to work pretty hard, in fact, to sleep as much as I think we would naturally, other than maybe my teenage son, he's fine if I leave him alone, so What happens to people if not? You don't get enough sleep, so in the lower body we know that short or insufficient sleep will worsen your cardiovascular system, increase your blood pressure, increase the rapid contraction of your heart and reduce which is not a good thing. called variability of your heart rate and therefore first of all we see significant impacts on your cardiovascular system and this is the reason why short sleep throughout life increases a whole collection of cardiovascular diseases such as atherosclerosis and We published an article about this recently that just Poor quality sleep and fragmented sleep increase inflammation and that inflammation leads to the buildup of plaques in the arteries and that leads to cardiovascular disease.

The next thing we talk about is the immune system. There is a very intimate association between sleep health and the immune system. health, for example, we know that people who have done some of these experiments also if you limit someone to just four hours of sleep for a single night, there is a 70 drop in critical cancer-fighting immune cells called natural killer cells. and So, you know, quite a worrying state of immunodeficiency after a little bit of sleep and that's just one night of short sleep, yeah, and we also know that, for example, and we just got the data covertly, same thing It's true here.

But if you don't get enough sleep in the week before getting a flu shot, you'll only produce 50% of the normal antibody response, so the vaccine you know will be much less effective, if not at all. I think the other big find is the burst. On the scene and I think probably the most interesting finding recently in sleep science is the link between lack of sleep and Alzheimer's disease and we do a lot of this. We have multiple major research programs looking at this at my sleep center. The first thing to understand is that people who don't get enough sleep, who sleep six hours or less, or people with insomnia, or people with a sleep disorder called sleep apnea, all of those people have a significantly higher risk of developing Alzheimer's disease in the future, now the problem is that that is only correlational, not causal, so the correlation went in search of causation and we found evidence in both animal and human studies, for example, if you take a healthy human and you deprive them, you selectively deprive them of just their deep sleep or you deprive them of sleep for an entire night, the next day we see an immediate buildup of the toxic proteins associated with Alzheimer's disease called beta amyloid and Tau protein, and we see that circulate in the bloodstream, circulate in the cerebrospinal fluid and use special brains.

In the scans we were able to see that it accumulates in the brain itself, so it was a causal demonstration that lack of sleep is associated with an accumulation of Alzheimer's disease proteins. Reverse that question, though if lack of sleep increases Alzheimer's proteins, then what? Is it the sleep when you get it that reduces those proteins and eliminates your risk of getting Alzheimer's disease? Well, then we found out and this was a find. By doing Netigard at the University of Rochester, he discovered that the brain has a cleansing process. Now we knew that the body had one called the lymphatic system, but we didn't really believe that the brain had its own cleaning system, but it does, but it's called the lymphatic system, named after the glial cells that make it up, but then we did more . discoveries which is that that cleaning system in the brain, that sewage system, is essentially not always on at a high flow volume during the 24 hour period, in fact, it is only during sleep and specifically during deep sleep that the brain turns on that cleaning system and washes itself. removing all the metabolic detritus that has been accumulating during the day is gross and hyperbolic, but you could certainly say from a biochemical perspective that wakefulness is low-level brain damage and what we have now discovered is that sleep is its salvation sanitary. and so it's a good night's clean sleep so to speak, it's an energetic cleanse for the brain, there are definitely some interesting analogies elsewhere, so I guess if you think about muscles, we all know that.

I guess from people who talk about training, you actually know the drill. Using muscles causes damage and rest and recovery are essential. We talked about you know areas where I spend more time around the gut, like how importantly it's now become clear that long periods of time need to be left for the gut to recover as well. and that's partly to make the microbiome but partly to make these processes, so it's really interesting that in all these different areas of the body you see the same thing in the brain and that sounds a little bit like my mother saying, well, you need have a break, you should let your mind rest.

It's funny too how some of this stuff feels very similar to the traditional advice our parents and grandparents would have given us and that maybe it's become harder to follow now that we have all this fantastic stuff. devices that can keep us awake all night Yes, I often say that really all I do as a sleep researcher for the last 20 years is put the science behind everything your mother told you about sleep so well. I've always believed that doing what your mother tells you is a good idea even if I don't always succeed so you know, that's the relationship, yeah, but let me get back to the things that we're doing together, I mean, it's incredibly exciting because you already know.

With many of the studies that we and other colleagues have done in the field, when we measure your sleep, we'll typically measure it for just one night in the lab because it's hard to constantly track individual humans, you know, night after night after night. It's especially difficult to track a large number of them from one night to the next, and then it's even more difficult to measure many changes in your brain and your body as a result of that continuous evaluation of tonight's sleep. We know a lot about what we call cross-sectional, so we just take a large group of people, record one night of sleep, measure the changes the next day and show that these associations exist, what it doesn't really tell you, though, is which one.

It's the consequence within an individual of the variability in their sleep over weeks, if not months, and that's a fundamental question because that's the way most of us live our lives, so what I'm saying is that we have not really understood what is involved. -Individual differences are within an individual over time as their sleep fluctuates, what can we learn about that and how does it relate to things like the metabolic system and their immune system and do they have a microbiome which is the type of work we do? we can do in the Zoe collaboration and then we can also look at the genetics because of course, as you mentioned before in the podcast, there is a notable set of twins within the large data set that gives us the ability to look at There are a lot of different things, but one of them is genetic heritability and that is also very powerful and I can mention if you want a finding.

I will soon post one of the most fundamental questions we wanted to ask. Next is how you will wake up tomorrow morning and secondly, how you will maintain that wakefulness throughout the day. What is it about your sleep, your food or your genes that determines how well you wake up each day and how able you are to stay awake and you would think that we would know the answer to that question, but we didn't and we were able to answer it with the set of data and therefore we looked at over a thousand healthy individuals that also contained a large number of identical and fraternal twins and What we discovered is that how well you wake up the next day has nothing to do with the amount of sleep you get. you sleep relative to the average recommended by the standard population, but if you sleep longer relative to your typical sleep average, then you wake up more effectively, it takes you less time to wake up, the engine warms up faster in terms of operating temperature, which is what we call overcoming sleep inertia and then you're much better at maintaining that wakefulness throughout the day if you've been sleeping more than normal, the second part is we found out that it's not just about your sleep. , but also your food and specifically your breakfast, and what we found is that breakfasts contain slightly higher amounts of fat and fiber, but low amounts of simple foods.

The sugar in that type of breakfast predicted a much greater ability to wake up and then stay awake throughout the day. Next thing we find and you would think you know the innate levels of how alert someone is. You know you can find some people. who seem to have a crazy energy that you meet every day and other people who are a little more laid back, you might think that means it's strongly genetic, well we did a twin analysis and showed that using this genetics of the data set alone has a very small contribution in determining how well you can wake up and stay awake during the day and I think that is actually very encouraging because it means that you are not tied to a predetermined genetic destiny that most of how well you do.

What you feel when you wake up every day and stay awake throughout the day is determined by non-genetic, in other words, modifiable, influencing factors, andI think that's incredibly exciting. They both decided that it's personalized, it's not just one answer for everyone, but people are different. but I also think we see this in a lot of our research that you're less locked in by your genes and I think a lot of us have been led to believe over the last 40 years and I think that's really reassuring, because it suggests that there are still things that you can do to change this, so that's exactly the message that how you sleep and how you eat every day will decide how well you wake up and feel awake every day and whether you see changes.

You know, over time and I think one of the topics that we had a lot of questions about from our listeners was menopause, which is obviously a really big change that we touch on in a lot of places is something that's well studied. and what's happening there personally, I don't think it's necessary for anyone close enough, but we know that there are marked changes during what we call the perimenopausal type of period, so during menopause and both before and after, there really are increases significant in sleep disorders sleep becomes more fragmented when you wake up people will find it harder to fall back asleep and then there are the temperature changes temperature changes these hot flashes that people will experience why is it a problem?

Well, it's a problem at night. because it turns out that your brain and your body need to lower their core temperature by about one degree Celsius or about two or three degrees Fahrenheit to fall asleep and stay asleep and that's why you'll always find it easier to fall asleep in a bedroom. too cold than too hot because the room that is too cold is going in the right temperature direction to always sleep, but if you are having these changes within the body and brain that create a thermogenic effect that creates these bursts of heat that we call hot flashes, don't It's no wonder you're struggling to stay asleep, so menopause is certainly one of those times. periods where we see disruptions in sleep and then as we get older, unfortunately we know that probably one of the cognitive characteristics of aging, of course, is that our learning and memory abilities start to fade and diminish, and that's been known since a long time ago.

However, what we have also discovered is that one of the most reliable physiological signatures of aging is that sleep gets worse, and not just any kind of sleep, by the way, it is particularly the deep quality of sleep that we described earlier, which is actually essential for some of the cardiovascular functions for some of the learning and memory functions for some of the immune system functions, all of which change with aging, that is the type of sleep that declines most precipitously as we age and the worrying thing It's, by the way, that big sleep depression for deep sleep, we can at least start measuring it happening in your mid-30s, which is exciting to me because that means it's an opportunity for prevention.

I think you know that this is also one of the goals of the Zoe project. Of course, we have a Sitka model and we don't have a healthcare model and we don't really understand the question of what happens when a human being makes a mistake, how do you treat that disease, how before you get it. Until that stage, do you keep a human being in the right direction and healthy? And that is a model of health care rather than disease, which is what we have now in modern societies. And I think you know this is something that I passionately believe in and, um, I know it's very clear that sleep is one of these core pillars, right, that if you do it right, you can really improve your long-term health, and I guess that I stopped your flight midway, Matt, but I'm just saying, yeah, we're incredibly exciting, obviously.

We think nutrition is a very important part of this, but ultimately it's about understanding that you know the set of things you can do before you're really sick to try to make sure you put it off as long as possible, that's exactly what correct. and that's why I think this, you know, in some ways it's depressing to know that it's in the mail for all of us, you know, I'm now solidly reaching the foothills of middle age and I've already seen the changes in my sleep, I can notice them, but what if we could do things that could intervene and actually prevent that decline in deep sleep?

Could we, for example, even bend the arrow of Alzheimer's disease risk back on itself through superior sleep intervention in midlife, which is one of the things we're very excited to try to do at my sleep center and I think it's a brilliant transition to the last track and I would say that, personally, I've really realized that I'm over 40 now that I'm doing it. I don't sleep as well as I used to I used to be someone who considered myself a very good sleeper and there is no doubt that I am more easily disturbed than when I am disturbed I find it harder to get back to sleep and this is even after using all your great advice but Should we transition to that?

Because we always like to make sure we give practical advice and I know you have some really great advice for people listening to this and now saying you know what maybe I didn't take. I sleep as seriously as I should have by now I want to take it really seriously How can I sleep better? What would be your advice? No. I think there are a couple of general tips and you can find most of them on the Internet as well. but it is good to review them, the first thing is regularity. I would say if you could focus on one thing, go to bed at the same time, wake up at the same time, no

matt

er if it's a weekday or a weekend, and I'm pretty. religious like this, you know, and not because I want to be an example of good sleep, it's selfish, you know, if you knew everything I know about sleep and how important it is, you would do nothing but prioritize the size of your I dream and I do it.

I would say make sure you have seven to nine hours of opportunity to discover what is innately right for you, called your chronotype. Are you a morning and evening type somewhere in between and need to sleep in? harmony with your chronotype to get the best sleep possible, so I'm somewhere in between like the rest of my personality. I'm pretty vanilla in terms of my chronotype, so you're either a morning and evening type or neutral and I'm mostly neutral I'm between 11 and 11 30, you know, 7 30 7 45, time to wake up, which puts me in the neutral category if I went to bed, you know, at 9:00 p.m. m. and then I would wake up. eight hours later or going to bed at 4:00 a.m. and waking up eight hours later versus my natural sleep window of eight hours, well, it's eight hours, so what's the difference?

Surely there is no difference, well there is a big difference because in one of those three scenarios I will have been sleeping in sync with what my biological rhythms want me to do and the other times I will be out of sync and not sleep as well, but the first message is regularity and Matt just a question because Know we're going to get a flood of these questions later, how can you figure out your chronotypes so you know you can sleep in line with that? If you want to do a detailed assessment, you can go to Google and you can search for something called m e q, which means morning and evening, the questionnaire will take you about three or four minutes to complete and then you will get a score and that score will tell you, in fact, really We use five sleep science categories for the extreme morning type. neutral morning type evening type extreme night type and it will put you in one of these flavors otherwise you could actually do it which is like my quick rule of thumb and it's just a rule of thumb it's not really a rule let me ask you the next question if you're on a desert island nothing to wake you up with nothing precious no one to wake you up without work what time do you think you would like to go to bed and what time do you think you would like to wake up and the answer to that question is usually very different from today, when you have to go to bed and when you have to wake up, and that mismatch is the misalignment between how you are forced to sleep and how you are biologically designed. sleep, so that's another way to answer the question and it's relevant to the way some people come to me and tell me I have severe insomnia.

I get into bed and I can't fall asleep for the first hour or hour and a half and then we do this exercise of discovering their chronotype and what you realize is that they go to sleep at 10 pm because they have to get up at six to go to work and in fact they are much more of a nocturnal type, normally they would like to go to bed maybe 12 12 30. So they don't necessarily have insomnia, they have this mismatch between their chronotype and when They start sleeping a little closer to their natural sweet spot, they sleep better. it's relevant to know your adult type, that's great and we'll provide links in the show notes to the questionnaire for anyone who's listening to this and we'll make sure it's the right one, yeah, and other than that, I'd probably go through it quickly. some other um temperature that we've already talked about um keeping your room cool aim for around 65 to 67 degrees Fahrenheit or around what is that 18 18.4 degrees Celsius I know it sounds cold but it must be cold you can keep your feet warm bottles of hot water socks that's fine, but the environment has to be cold and that's colder than a lot of people keep their rooms nowadays, that's right, yeah, most people will come home, set it up, you know , they have this 70 72 degree room temperature in the house and then they leave the same thermostat setting for the night and we need to cool down at night so keep the temperature in mind.

The light is something else. We are a society deprived of darkness in our modern era and we need darkness at night to activate liberation. of a sleep hormone called melatonin, so as a tip, I don't like the word hack, but as a tip, try doing the following experiment in the last hour before bed, so set an alarm on your phone or your home device, say you know. set the alarm for and whatever time it is now before you go to bed and in that last hour dim half of the lights even more lights if you can dim half of the lights in your entire house and you will be surprised how sleepy you get The increase in darkness will make you feel and what that tells you is that normally you are suppressing the release of this sleepiness hormone, melatonin, or it is a hormone that synchronizes sleep when you are bathed in electric light at night, so the light is another one of the last two things I would mention alcohol and caffeine I know, I know, I'm sorry this is bad news yeah you're a bit of a downer with this Matt I have to say it but I think you should tell everyone so that they understand all the facts well. much more optimistic now, you know, some people sometimes on different podcasts when they interview me say: do you know how you've changed your mind in the last five years?

I have changed my opinion about coffee. I would say that you drink coffee because it is healthy. The benefits that have been associated with coffee are profound and very reliable, but here when it comes to sleep, the dose and timing are poisonous, by the way, the reason why coffee is associated with health benefits is not It has nothing to do with caffeine, the reason is because the coffee bean contains a huge dose of antioxidants and because most people and you know better than most of us, Jonathan, most people in The Western world have poor dietary intake and the way most people get their daily dose of antioxidants is through their cups of coffee and this is why coffee is associated with health benefits.

For example, you get very similar health benefits with decaffeinated coffee, so it's not the caffeine, it's the coffee bean itself, but I would say the dosage and timing makes the poison try to limit. drink two cups on average, maybe three, but the key thing is to stop at least 12 hours before going to bed, that's a good rule of thumb and I would say that alone I am more addicted to tea. than coffee, but I have definitely found that this moment with caffeine is important and now I stop. I think this is something you can discover for yourself.

Matt is somewhat right because there is a lot of personal variation in the response to caffeine. Isn't there? Yes, there is and we know the genes that change the elimination of caffeine, the rate of elimination of caffeine, but in my case that means I have to go around two or three in the afternoon and if I go later, then sure. You know, it affects my sleep and sometimes it can also mean that you wake up again right in the night and then can't go back to sleep, so it's a little more complicated than I had imagined, yes, both make it harder to fall asleep. dream that fragments your dream but the other thing that ispernicious about caffeine some people will say look I'm one of those guys and they might be because they eliminate caffeine very quickly but not fast enough as we'll see, they'll say I can have an espresso with dinner and I fall asleep and I fall asleep and I'm fine, even if that's true, caffeine can actually decrease the amount of deep sleep you get by 12 to 15 percent, it depends on the dose of caffeine we take.

I've done this in our lab now to reduce your deep sleep by 15. It would have to age you 10 to 12 years, or you can just do it every night with an espresso. It's a bit correct. Be considerate. Hey, what's up with the alcohol? Yes, you know that many people, when they have difficulty sleeping, turn to alcohol as a quote-unquote sleep aid, unfortunately, it's anything but a sleep aid. Alcohol is not a class of drugs that we call sedatives and sedatives. It's not sleeping, so when you have a couple of drinks to sleep people say look, I always fall asleep faster, if I've had a few drinks at night, you're not actually falling asleep faster, you're just losing consciousness faster. quickly and that's the first.

The problem of alcohol is a sedative. The second is that alcohol will fragment your sleep like caffeine, but through a different chemical mechanism, so you will wake up many more times during the night, but the problem is that you usually don't remember those awakenings, so you wake up the next morning. When you wake up you feel understood and not rested, but you don't remember waking up, so you don't put two and two together. The final reason why alcohol is not good for sleep is that it is quite powerful at suppressing your REM sleep or sleep. Sleep and we know that dreamed sleep, as we have talked about, has many benefits for the brain.

It is also essential for the body. REM sleep is the peak time during the 24-hour period when men and women release their maximum levels of testosterone, for example. so we need REM sleep, so I'm very nervous as a scientist about telling someone how to live their life. I don't think I have anything to do, what I'm here to do as a scientist is simply impart the knowledge so that you can then make an informed decision about how you want to live your life and of course, oh my goodness, when it comes to cups of coffee , and you know that having a drink from time to time, life is lived for the love of God, so don't get carried away.

He's a puritan about it, but I only know the evidence and I know there can be consequences. By the way, I would say with alcohol the politically incorrect advice I would never offer you would be to go to the pub in the morning and that way the alcohol is out of your system at night and then you'll be fine, but I would never say such a thing on a podcast. health and we did a whole podcast on alcohol and I think it's very interesting topic, but I think the impact on sleep is clearly one of the big drawbacks and Matt, one thing that you haven't mentioned but that was very influential for me was Make your room like a cave so they don't wake you up. in the morning is something that you still think is really important, yes, a lot, so this is the temperature, so it's not just about the temperature, but it also combines the third tip that I mentioned, which is darkness, so Keep your room cool and dark, and then you know.

If you need to, you can use earplugs or sound equipment. We don't know much about stereos, whether they're useful or useful for sleeping right now. I think for the most part they seem to be benign right before they end. I think one thing I noticed you didn't mention is screens and that comes up quite often. Yes, yes, it's a good question. You know, this comes back to the issue of light, particularly light exposure at night, and unfortunately, our screens are enriched with blue. The LED light spectrum, which is the worst for our melatonin levels, suppresses it the most strongly.

I would say probably more than 50 to 60 percent of the studies that look at blue light screens have an impact on sleep, but some of them haven't found a strong effect. What we do know now is that those devices perhaps the biggest detrimental impact on sleep is not necessarily light, but they trigger interaction because when you are on these devices, particularly your phone, it is designed to capture your attention, make you alert and it will keep you awake, sustained and engaged and many people will have what we call sleep procrastination, where they are perfectly tired but they are so busy with their device that they can't put it down, what it seems to be, if anything, is this state of alertness which actually otherwise masks very bad drowsiness, so my rule of thumb again is not to go puritan: the tech genie is out of the bottle and it's not coming back in anytime soon, no

matt

er what I say, so ya You know, use your phones and your screens, just keep it there.

Keep in mind that they can have an impact on your sleep and the general rule is I prefer people to keep their phones out of their room if they absolutely have to be brought into the room. Here's the rule: you can only wear them in the standing room. I haven't heard that before, yeah, it's really interesting, you think okay, after about five or six minutes, I'll just sit on the bed, no, at that point, that's the rule, you're done, put the phone away, that's how it is. Brilliant and I have to say that staying out of the bedroom is one of the things I've become quite strict about, but it's not always an easy thing to do.

I would like to conclude quickly as we always do. and make sure to summarize what has been, as always, a very broad conversation, so I think, first of all, know that the big message is that sleep is incredibly important, you need seven to nine hours, whatever that is to you, and if you don't. has these really profound health impacts, we talked a little bit about the studies we've been collaborating on together and this really exciting new paper coming out shortly about how we wake up every day, how we can stay awake, and how different we we are each of us talked a little about sleep disorders around menopause you gave us a lot of advice regularity discovering your chronotype cooling your room finding a way to make your room very dark both when you go to sleep and when you wake up and then i think you've become a little softer on caffeine and alcohol than maybe when i read the book a few years ago, but in general coffee is probably fine, but make sure it's well before you go to sleep, alcohol, believe.

You're basically saying that you know it's probably never going to be really good for you, but keep that in mind and in terms of screens, if you're going to bring them into the bedroom, you have to stand up. Excellent summary Matt, it was a real pleasure and we hope to speak again in the future. I hope the next article we publish sounds good. Take care of yourself. Thank you for taking me in. Jonathan. I really appreciate it and thank you for the collaboration we have. I think it is immensely powerful and it is a privileged opportunity. data set, so thank you very much, you're welcome, thanks Matt, bye, thanks to Matt Walker for joining me today on Zoe's science and nutrition.

We hope you enjoyed today's episode, if you did make sure to subscribe and leave us a review. We read all the comments. If this episode left you with questions, send them to Instagram or Facebook and we'll try to answer them in a future episode. Zoe, we want to improve the health of millions by understanding what is the right food for each one. of us to improve our health and control our weight, each member starts with an at-home test that compares them to participants in the world's largest nutrition science study. If you're interested in learning more about Zoe, you can join the zoe.com podcast and get 10 off your personalized nutrition program as always I'm your host Jonathan Wolfe Zoe's Science and Nutrition is produced by Fascinate Productions with support by Sharon Feder yes, like Ewings Martin and Alex Jones here at Zoe, see you next time.