WHOOP Podcast - The Science of Sleep: What sleep does for your body, mind, and cognitive functioning

Episode Date: October 20, 2021

Renowned sleep expert Dr. Meeta Singh joins the WHOOP Podcast for an in-depth discussion on the science behind sleep. Dr. Singh is a board-certified physician and psychiatrist with deep expertise in sleep, sleep disorder diagnosis, and treatment. She has worked as a consultant for multiple NFL, MLB, NHL, NBA, Olympic, and college sports teams, as well as for large organizations. The Washington Nationals considered her work so vital to their championship in 2019 that they gave Meeta a World Series ring. She sits down with WHOOP VP of Performance Kristen Holmes to discuss society's disregard of sleep (5:01), the stages of sleep and how it progresses throughout the night (12:16), sleep need (15:10), why poor sleep leads to poor decision-making (23:16), understanding caffeine (27:02), sleep consistency and metabolic health (33:43), why meal timing is important (39:38), sleep's role in mental health (50:06), major factors that lead to poor sleep (1:02:10), and why sleep is the ultimate life hack (1:04:38). Support the showFollow WHOOP: www.whoop.com Trial WHOOP for Free Instagram TikTok YouTube X Facebook LinkedIn Follow Will Ahmed: Instagram X LinkedIn Follow Kristen Holmes: Instagram LinkedIn Follow Emily Capodilupo: LinkedIn

What's up, folks? Welcome back to the WOOP podcast where we sit down with top athletes, scientists, experts, and more to learn what the best in the world are doing to perform at their peak and what you can do to unlock your own best performance. I'm your host, Will Amit, founder and CEO of Woop, and we're on a mission to unlock human performance. This week, we're excited to welcome Dr. Mita Singh for an episode on The Science of Sleep. This is the first of a three-episode series, which also includes the science of recovery and the science of strain, which are coming soon over the coming weeks. The science of series is meant to simplify the science behind these concepts, answer common questions, and debunk myths. Okay, back to the talented Dr. Singh, a board certified physician and psychiatrist. with deep expertise in sleep, sleep disorder diagnosis, and treatment.

So she's worked as a consultant for multiple NFL, MLB, NHL, NBA, Olympic, and college sports teams, as well as for large organizations. The Washington Nationals consider her so vital to their championship in 2019 that they actually gave Mita a World Series ring. So Dr. Singh sits down with our VP of Performance, Kristen Holmes, to discuss the science behind sleep and what it does for your body, your mind, and your body. cognitive function. They cover how sleep plays an important role in decision making and learning, the relationship between metabolic health and sleep consistency, and everything you need to know about

sleep debt and how to manage it. As a reminder, you can use the code Will, that's WI-L, to get 15% off a WOOP membership. WOOP membership includes hardware and software and analytics designed to help you improve your health. And of course, it now includes the new WOOP 4.0. So check that out at whoop.com. Without further ado, here is Dr. Singh. Dr. Mita Seng is a board certified physician and psychiatrist, concentrated in the applied science of sleep. Her evidence-based approach integrates individualized, medical, psychiatric, and behavioral diagnosis and coaching to improve clients' sleep health, to optimize physical and mental performance and enhance health and quality of life.

Dr. Singh's deep experience in sleep disorder, diagnosis, and treatment was forged in psychiatry at the Mayo Clinic and as a physician in sleep medicine at the Henry Ford Sleep Center, where Dr. Singh practiced and served as chief of service for 15 years. We truly admire the work Dr. Singh does to provide evidence-based guidance to help folks get the sleep that they need so they can perform to their potential. Dr. Singh, welcome. Thank you, Kristen. and thank you for that very kind introduction.

Oh, well, your work is just insanely inspiring. So fun facts, Dr. Singh has a World Series championship ring from her work with the Washington Nationals. Meena, that must have been an amazing journey. That was an amazing journey. Thank you so much. And I have to tell you, like the most interesting part of that was great teams. They always want to do better. They're always there.

and then they're competing against other people who are there. So they're looking for that small edge, anything that will make them do better, and they listen. And that's, that's, you know, when you're, it's like a ball that gets rolling, or actually a snowball, you know, when it's coming down as well as it is, it's larger and larger. And as the season progresses, especially the postseason as they get better and better at what they do, you know, they really want to like become,

tighter and tighter with all the things that they want to optimize. And sleep is so important. I love it. Yeah. I mean, you make a great point. I mean, when you look at that kind of top tier, you know, the genetics and the genetics, I mean, it's all basically the same, right? The coaching, like everyone is tremendous, right? The difference makers truly in the performance lifestyle, you know, and obviously a huge piece of performance lifestyle is kind of our choices around sleep. So I love that. So to kick us off here, Dr. Singh, can you explain to me? why human beings are the only species that deliberately deprive themselves of sleep for no apparent reason? I would say that in the wild animals, if they were in danger or if they were,

you know, if they were in desperate conditions, they probably would not sleep because they have to be hyper aware and they have to be, you know, they have to be on guard. But for some reason, we as human beings, we do this on a regular basis and we're not in danger. But I think what's happened is that we live in this 24-hour society, right? It's 24-7, we're always on. And especially in the culture that we live in, in which Kristen, we're always trying to achieve more. We're trying to make sure it's like we live in a hard. hustle culture, oftentimes we feel that the number of hours that we can put in, the greater

the number, the better it is. And when we talk further, we should, we should talk about this more because that's not true, right? Because it's, there's a difference between smart work and working hard, you know, and smart work means you want to, whenever you show up for whatever work you do, you know, good, effective smart work is a function of a well-rested brain. And we often forget that. There's, you know, that's that's one thing. And the second thing also is, for the longest, sleep was considered to be optional. It was considered to be something that I'll sleep when I'm dead.

That culture was around. And that's slowly changing. So people still have that. that's and and the third thing i would say is that um there's also this you know when it comes to sleep um especially when it comes in in work organization you know in large organizations leadership really can change the culture about when it comes to rest and sleep so if if the leader is sending out emails at three in the morning well you know that means that they're not getting enough sleep. And if you want to do well, you realize that, well, you know, if they're sending out

an email, even if you, even if the leader expects the email back, a response back at six in the morning, if you're a worker who wants to show that you're committed to the company, you send an email back at the same time. We'll talk a little bit more about sleep and learning and memory, so kind of dig into that. And I'd love to talk to, too, about presenteism and chronobiology, so we can kind of dig into workplace a little bit. But before we do that, and we'll talk, and we'll also talk about the various systems in the body and kind of what's happening when we're operating a short sleep. But first, I think in order to fully appreciate the strength of a full night's sleep, we kind of need to understand what is actually occurring in our brains from the

moment we fall asleep to the moment we wake up. So I'd love for you to kind of talk us through what is happening during this incredible journey. We call sleep and perhaps a bit about why it matters. So let's start out with what sleep is. So sleep is a normal behavior. It's a normal physiological behavior that occurs every 24 hours. And it's disengagement from the environment as well as unresponsiveness to the environment. Right. So and and as far as we know, you know, all organisms at every level show some sort of rest activity cycle. So it's the rest part. And while we as human beings, while we're asleep, because our brains and our bodies are forced into inactivity, rest and recovery tends to occur during that time. And when people, you know, people, when you know, when you ask them what sleep is, they said it's restful.

It's when you, you know, you turn your mind off, et cetera. And although people look very passive while they're asleep, your brain is very. reactive. And so there are different neurochemicals being secreted. And as the neurochemicals are being secreted, there are different brain waves that are being formed. And it's like a concert. And the brain goes through different stages of sleep. And each stage of sleep is important and serves as a different function. And so, you know, in the brain, because there's inactivity, it's, it's, like hitting a reset button that happens at night and that prepares you for the next day. Now, sleep scientists, you know, much to our chagrin, we don't really know what the overall

function of sleep is. We know it's really important, right? You spend a third of your, or you should be spending a third of your life sleeping. So unless it serves something absolutely essential, it would be a complete colossal wastage of time. Like, why would you be doing that? you're, you know, while you're asleep, you're vulnerable, you're not, you know, you're not doing anything useful. So we definitely know it's very useful. And, you know, recently in the last few years, there's been research that shows that while you're asleep, blood sort of rushes to your brain and your brain gets power washed of all the toxins that have been accumulated during the day. And so that might be a very fundamental thing that happens during the sleep. And so that

prepares you for the next day. Maybe if we can focus on just one aspect, we got a good question from one of our listeners wondering about REM sleep and what exactly is happening during REM and sleep. And should they be concerned about the percentage of time they're spending in each one? Is there an ideal time? Is the body driving it? What are your thoughts on that? wonderful so so let's perhaps let's give a broad overview of what all the sleep stages are so like i said you know different neurochemicals are being secreted and your brain waves look different so typically sleep or the state of human you know that human beings are can be divided into three parts you're either awake or you're in dream sleep or rm rapid eye movement sleep or you're in

non-dream sleep. Now, non-dream sleep is divided into three stages, going from the lighter to the deeper stages of sleep. Light sleep is N1, then N2, which is slightly deeper. N3 is deep sleep. And, you know, when you're falling asleep, you fall into sleep through light sleep, then go into deeper stages of sleep. And during light sleep, you know, your breathing slows down, your heart it goes down, your blood pressure falls. And during your deep sleep, which is an N3 or delta sleep, is where most of the restoration tends to occur. Deep sleep is really, really important because it's important for memory. It's where, you know, your muscles are completely relaxed, you know, you're storing, you know, glucose. And that's when muscle recovery is typically

have is happening and and then during dream sleep dream sleep tends to occur in the second half of the night and dreams during dream sleep uh learning and memory it's important for learning and memory but it's also important because it adds emotional context to our memory so it so every stage of sleep has a certain function you know it's not as if light sleep is less important than deep sleep is less important than dream sleep. And typically, you know, light sleep is pretty important. We spend about 50% of our sleep period in light sleep. And there are certain brain ways. Light sleep, that's a bad rap. But light sleep is simply. Yes. It does get a bad. Yes. And then, you know, and then deep sleep is approximately 25% of your total sleep time period.

And I will tell people, two more things I want to tell them. So first of all, most of your deep sleep occurs in the first half of your night. So if you fall, sleep, you know, deep sleep will haka in the first half of the night. Dream sleep tends to occur in the second half of the night because dream sleep is driven by your circadian rhythms. That's one thing. And the other thing is that we progress through night in different stages of sleep. So you go to light sleep, deep sleep, dream sleep, and then your sleep lightens and you may actually wake up. And that's a, that's a sleep cycle. And it's approximately 90 minutes. And you cycle through these different, you know, you do different stages all through the night.

Okay. So the other thing that I think comes up a lot and there's perhaps a lot of misinformation around is whether or not we can catch up on sleep that we've missed, right? So we all have like a base sleep need. So maybe, you know, talk about kind of what that might look like for folks in terms of how much time they need to be spending in bed. And then if they're not getting the sleep that they need and they're accumulating sleep debt, you know, what is actually happening there? And can they kind of catch up on last, on lost sleep? You know, when we are thinking about sleep, a good way to think about sleep is to think about the quantity of sleep, the quality, and the timing of sleep. So let's first talk about the

quantity of sleep, which is what you were saying is sleep need, right? So of course, you know, the American Academy of Sleep Medicine says for adults, you know, adults need about seven to nine hours of sleep to function well and optimally the next day. Definitely if you get less than six hours of sleep, you're going to see deficits in your performance. It also changes with age. So young, you know, kids need more sleep, you know, babies need a lot of sleep. And as you get older, your sleep requirements slowly reduces. Adolescents still need about nine hours of sleep. Younger adults tend to need more sleep than older adults.

Now, there is human, you know, there is variability. So, you know, my sleep requirement may not be yours. But, you know, think about what sleep need is. So sleep need is the amount of sleep you need to be alert and aware. in quiet, dull, boring situations the next day, right? So normally when you're, say, sitting down and you're, you know, if you're doing something on your computer or if you're, you know, listening to this podcast or, you know, watching a TV,

even if the situation is boring and you're sitting, you know, you should be able to keep yourself awake. Right. And so adults shouldn't really feel sleepy during the day if they're meeting their sleep need. Well, it's not as simple as that. Most times when people meet their sleep need, they should be alert the next day. But alertness varies in a 24-hour cycle, depending on your circadian rhythm. We'll come to that. So it's not, you know, if you if you're meeting your sleep need and if you're well-rested at night, when you wake up in the morning, you know, you should once you get going, you should feel you should be alert. In the mid-hour, you afternoon, there should be a normal, you know, dip in your alertness. And then you should become alert again. And in the evening, you kind of sort of catch a second wind before your bedtime. That's how alertness varies during the day. That's the definition of what your sleep need is.

And I tell people, you know, one way to think whether you're meeting your sleep need is if you're able to, if you feel, you know, well, rested during the day, or if you think that, you know, you can get by in your day without having to caffeine up. That would mean that you're well rested. Yeah, that's a good, kind of a good worker. Now, you know, most people have some amount of sleep debt that's going on. So most people, because of, you know, all the things we discussed earlier, are not getting enough sleep on a regular basis. And if you get less sleep on a regular basis, sleep debt, which tends to accumulate over time. That's the definition of sleep debt. And the best way to recover from that is to play catch up, is to make sure that whenever you get

a chance, you want to sleep in. One way to make sure that you're getting enough sleep is to monitor how much sleep you're getting on a regular basis. So if during your work week, if you get you know, a certain number of hours of sleep. But then on your, on the weekend or your days off, you sleep longer as compared to what you're getting habitually during your work week, that is an indication that you're trying to play catch up. And that means you were not meeting your sleep need when you were on a regular basis. So that would be a good indication to make sure that you're, that you're not getting

enough sleep. So in an ideal scenario, we're, you know, going to bed and waking up at a very similar time. and we're, you know, consistently meeting our sleep need. But of course, life happens. So you're suggesting to just extend our sleep when we have the opportunities to in order to kind of catch up. I tell people, even small increments, how? So, you know, if on a regular basis you're getting six hours of sleep,

well, perhaps go to bed 15, 20 minutes earlier. Just do that for a little while because that will mean a little bit more sleep. And then, you know, once you're able to do that, maybe perhaps go to bed another 20 minutes earlier or just try and stay in bed a little bit longer. And that itself will help without trying to make sure that it's all on the weekend or on your days off. Right, right. And I, you know, personally, obviously I just listen to whoop, you know, so a whoop does all the work for me. And I'm super alert when I need to be alert. I'm sleepy when I need to be sleepy. So I definitely take advantage, obviously, the technology. So let me just intervene that. I mean, and that I think is a

great way to use whoop. Yeah. So we live in this society where we really want to measure quite a bit. Right. And I would say looking at how much REM sleep you've had or deep sleep you've had, not sure how useful that is. Because what are you going to do with that information anyways? Like if it tells you, you know, you have less REM sleep or less deep sleep. But since stages of sleep are a percentage of the total sleep time. That is really useful information. So if you wore a device and you looked back at the last two weeks and you say, well, you know, every Tuesday night for some reason I go to get really less sleep and then, you know, all to the week I'm getting less sleep and then, you know, here comes Saturday. You know,

I sleep in, et cetera. That's the kind of information that's really useful because now you can look at trends. You can relate that to the behavior. that you've been doing during the day, and then you can take, you know, you can take insight from that and make behavior change. That, you know, then it becomes a very useful tool. Yeah, definitely. We did a really interesting study with about 100 CEOs, and we looked at, you know, all sorts of parameters, but we're looking at sleep and heart rate variability in relationship to executive functioning. And, you know, one of the kind of happy findings in the study is that we were able to see that a relationship between sleep debt, which is basically what whoop says you need versus

what you actually got, that delta actually correlated to next day executive functioning and working memory measured via Stroop and Mback. So it kind of indirectly validated whoop sleep need. So it's not just a random number generator. It's actually, if you kind of listen to it, and obviously we're considering circadian factors, like, you know, there's a lot that kind of goes into the recommended recommendation of sleep need, and it's based on a lot of physiology and science. But it was really cool to kind of see in that study, you know, a relationship. And basically, you know, what we saw for every 45 minutes of sleep debt you accumulated, there was a 10% decrease in executive functioning and working memory next day. So a lot of these CEOs meet it. And you work

with these folks, right? I mean, they have significant sleep debt. I mean, we're talking for some folks, it's like they're missing their sleep need by three hours. So that's like almost 30% decline in executive functioning working memory. And we saw this, you know, and so I thought, yeah, that was crazy. Just meeting that sleep. I want to pick on one, a couple of things that you just said. So something really important, sleep, the effect on performance the next day, any deficits in your physiology, the next day occur in a dose dependent fashion, which means getting five hours hours of sleep is worse than six hours, worse than seven hours. Does that make sense?

So which is what you're saying for every, you know, 30-minute increments, the less sleep you get, the worse it gets. And that's really, really important to understand. I mean, that's been shown in many studies. You know, you look at reaction time. You look at, you know, you look at accuracy. It's always, you know, the less sleep you get, the worse it is. And the second thing is those definitely. So if you continue to get less sleep, it's going to get worse.

So that's number one. The second thing is I think this is also a great time to discuss, you know, what executive functioning is and the components and how, you know, sleep affects it. So think about all the aspects of executive functioning. So, you know, one of, you know, making high level decisions, flexibility, which is the ability to change, you know, in the middle of a project or in the midst of a game when you're telling the coach decides, well, this is not working. This is what I want you to do. You know, for athletes, the ability to say, well, that didn't work. I'm going to, like, switch gears.

So that hyper-responsiveness, again, function of a well-rested brain. When you don't get enough sleep, that part of the brain that is responsible for good judgment, decision-making, multitasking, you know, high executive functioning tasks, that gets preferentially impaired when you're asleep, when you don't get enough sleep. And that part of the brain, and actually there's one part of the brain that sort of lights up, which is your emotional brain, for some reason, it becomes overly active. And so, you know, your decision making definitely gets impaired. You're likely to take, you know, you try to, likely to put yourself in risky situations because because your judgment is impaired.

So that's one thing. The second thing is that, of course, learning is really important, right? So learning, anything you learn during the day, your brain hits the save button while you're asleep. One of the functions of deep sleep is to prune all this unnecessary information that you may take in and keep or retain that information that is really important. I mean, isn't that like you don't want your mind crowded with, necessary stuff. One of the things you do in

an executive as an executive is you take in all this information and you come up with these novel solutions. I mean, you know, for example, in the NFL, right, they're watching film, they're looking at what's happening and then they make decisions based on that. Well, that is creativity.

That is, that only happens when you're in your sleep. You know, you take this previously stored information, you put it together with new information, you come up with this novel solution. You know, not getting enough sleep, you make poor decisions, you're not likely to, you know, pick the correct project. You know, you're likely to not score the risk value correctly. And most of all,

your emotional intelligence get impaired. And I think that's so important. So emotional intelligence is just awareness of your own emotions and the ability to name them. And and then help manage it and to have empathy, all those things that make you a good leader, a good coach. You know, that's, again, it's a function of a well-rested brain. If you don't sleep well enough, you know, you can't really read that. You can't really do that. You can't really read other people's emotions

if your own emotional functioning is not, you know, happening correctly. And I think what happens is that because, One of the first thing that happens is that your judgment is impaired. People's awareness of this doesn't exist. That is why tools are good. So it's funny because if I give somebody a tool, you know, a device and say, well, I want you to wear this, I want you to do this for about three weeks and they're like, well, I'm getting enough sleep. And then you look at the data afterwards and you tell them, well, not really. You really aren't.

Because if you went into, if you got into bed at midnight and woke up at four and four and, in the morning for a board meeting, they want enough hours. So you can't say you've got more than that sleep. Right, right. So, Meena, you know, we work with a lot of executives and tactical athletes and health care workers. And they really, you know, their perception is that short sleep, I can just remedy it all with some caffeine. Does caffeine improve decision making? Like, what's actually happening with that dynamic? So caffeine is a stimulant. And so to describe what caffeine does, we have to talk a little bit about how it works. Well, one of things we know really well is that the longer you stay awake, there is a neurochemical that accumulates in

your brain, which is like a sleepiness neurochemical. It's called adenosin. And so when it accumulates in your brain, you become sleepier. And what caffeine does is it goes and it attaches itself to that place in the brain where the adenocin is attached. So it blocks the effect of adenocin. So it is pretty effective in keeping your weight because it blocks the effect of sleepiness. So things like your reaction time, your accuracy do increase. You know, if you were playing something, a game, if you were, you know, in a sport, it does help in that. The problem is that And there's studies that show that it doesn't really affect your judgment. So decision-making doesn't get much better.

And so, you know, you're just making those bad decisions, but you're just making them faster because now you're all caffeinated up. And then, of course, caffeine does make you a little anxious. Like, it may make you jittery, it may make you a little hyper. So that's just one thing that, you know, that your audience should be aware of. You know, one last thing I'll tell you is that caffeine, of course there is, again, there's variability. Some people are fast metabolizers. Some people are your lower metabolizers.

Typically, the half-life is about four to five hours, which means that if you drink, you know, drinking a double an espresso after dinner doesn't do you any, doesn't help your sleep at all. And for some people who say, well, I'm still able to fall asleep, even if I drink a cup of coffee, what caffeine will do is it will, it will prevent you from going into the deeper stages of sleep. So it will still impair the quality of your sleep. So we're going to switch gears a little bit and kind of, I'd love for us to kind of tack our way through the reproductive, cardiovascular, metabolic, and immune systems and kind of what's actually happening on short sleep and, you know, how people can kind of develop a framework on, you know, hopefully it will inspire, I don't want to frighten people, but hopefully it will inspire people to really

prioritize sleep and maybe recognize. where, you know, if there are deficiencies, you know, to really encourage people to get some help. You know, I think it's easy to kind of go through life and, and, and, and, and, and, deprioritize sleep. And, you know, and it just seems like kind of this luxury. But, you know, I'd love for us to kind of make, for you to really make a case for why it's absolutely central, just because it is really impacting every physiological system and body. Right. Right. And the simplest way to start is that all the things we've been talking about so far, is what happens to sleep in the brain.

Right, right. But like we just said, every physiological function is affected. So think about, think of sleep as a nightly reset for your heart, you know, for your reproductive system, for, you know, your stomach, your heart, your lungs, your, you know, every, every part of your body is taking a rest. Sleep is, for example, very important for immune. community. And, you know, in the world we live in right now, you know, your immune function is really, really essential. So getting a good night of sleep is your best, is one of your best

bets for fighting infection. As long as you, you know, you do the right thing like mask up and, you know, you want to prevent physically getting in touch with infection. But, you know, when you're, it's while you're sleeping that your immune function, you know, your immune cells sort of, you know, there are these really cool cells called natural killer cells. And, you know, they get an natural night of sleep and get well rested and are prepared the next day. Also, once you do get an infection, you need sleep for that, that, you know, to be able to fight that infection so that you, it doesn't progress. That's how it helps immunity. I, you know, I just love the interaction of sleep and how it affects cardio-metabolic health.

And so, you know, and I'm going to tell you a story. I mean, just kind of follow along. And I know that, you know, in the last hundred years, there's been a steady decline in the amount of sleep people are getting. And at the same time, there's a steady incline in how they're gaining weight and obesity has increased. And there were multiple studies done in different populations that looked at the association of obesity and sleep duration. And the magic number was that anybody less than six hours, you know, seven hours or less, and especially six hours or less, more likely to be obese.

And then this was further studied. There was Eve Van Coutter and her group at University of Chicago. They took healthy young adults and they did sleep deprivation studies in which instead of, letting them get enough sleep, you know, make sure that they get only four or five or seven hours of sleep over a period of time. And these young, healthy adults, at the end of this sleep deprivation period, they were not utilizing their glucose. It was as if they were diabetic. Of course, this was reversible as soon as they got enough sleep. And they found that when people are sleep deprived, they are hungrier. They tend to consume more calories. And when they're

they consume these calories these calories tend to be carbohydrate rich fat and foods i mean they're not craving fruits and vegetables right right and then of course and then there is this very interesting relationship between with sleep deprivation and what happens to the hormones that control hunger and appetite and so you know your brain while you're asleep secretes a hormone called leptin which is a satiety hormone tells you that you're full if you don't sleep enough well not going to be secreted you're hungrier your stomach secretes you know grellin which makes you hungry if you don't get enough sleep you know you get too much of grelin and and perhaps you know perhaps when we were hunters and gatherers if we didn't get enough sleep it meant you were in danger

and you wanted to eat a lot of food so that you could conserve energy but of course you know now the hunting we do is when we get up to go to our refrigerators to eat yeah so there's that But the other thing, and, you know, we haven't talked about circadian rhythms yet, but the other thing is that all the studies found that that impairment in your metabolic control that happens with sleep deprivation is always significantly worsened if you bring in circadian misalignment. So if people start sleeping at times which are not their normal sleep times, which happens in, say, shift workers, or, you know, happens, like, for example, in nurses when they're doing this shift work, then there is an added impairment in their metabolic control as well as their reproductive health. Right. And, you know, there's some data that shows that if you're, you know, shift workers,

there's a high incidence of certain kind of cancers. The World Health Organization, you know, deems shift work a carcinogen, which obviously is. And then what shift work does is there's sleep deprivation. And association with that, there is that circadian disruption. So I want to just hang on the metabolic functioning and just in light of your comments around circadian rhythm, because I think that the common advice, of course, when folks want to lose weight is, you know, eat less and move more. Clearly, this is an oversimplification, right, given everything that you just said about

metabolic health and its relationship to sleep, sleep is where you should start. Actually, a lot of folks come on our platform and they check their motivation for getting on to whoop is to lose weight. and I think people don't always recognize this really strong relationship between sleep and weight loss and the ability to lose weight. So I'd love for you to talk, you know, I know you know Dr. Sachin Panda out of the Salk Institute. He does a ton of work around time restricted feeding. And, you know, I think in one of his recent studies, he basically showed that a 10-hour feeding window. So you basically have your 10-hour, you know, you only eat during this, you know, your strict eating, you know, in this 10-hour window.

So you're fasting for the other, you know, 14, they sought a three to four percent decrease reduction in weight, body mass index, abdominal fat, waist circumference, and then two of the key risk factors for heart disease, high blood pressure and high cholesterol also decreased, and then blood sugar and insulin levels improved too, which is not surprising. I would love to get your thoughts on just as a clinician, you know, are you helping folks kind of establish these feeding windows, kind of how much does that come into your practice? Well, that, by the way, is a fantastic question. And I'm going to give you a very long-winded answer.

Because I think for your audience, I think we should start out by talking about what circadian rhythms are so that they understand, you know, exactly where we're going here. So remember how we all we've, what we've really talked about so far is the sleep quantity. And remember I said, there's another thing called sleep timing. And so that leads us to what circadian rhythms are. Now, because we live on this rotating rock, Kristen, you know, our earth, and because we have alternating cycles of light and dark, all organisms, including human beings, we've developed these intrinsic clocks. So these are clock, they're timekeeping clocks, and circadian stands for circa, which is approximately 24 hours, you know, 24 hours. So for us, for human beings, our circadian clock is located in our brain. and it's a again it's an intrinsic timekeeping system but in in addition to be intrinsic

it's also on a daily basis it's reset by exposure to light and dark to wherever you are you know so I'm you know I'm on the East Coast in the US so when I wake up in the morning light enters my eye so my eye you know I use my eyes for vision to see things and for light perception for my circadian clock. And light actually hits my circadian clock before it even hits my visual center. And when light hits my circadian clock, it starts secreting an alerting signal, it keeps me awake during the day. And then in darkness, melatonin is secreted in my brain. And that signals my body that I'm ready for night time activity, which for human beings typically should be sleep. So that's our circadian.

That's our circadian clock. And so the clock in our brain is a master clock, but every cell in your body actually has a clock. And every physiological function has a circadian rhythm, which means that during the day it peaks and then there's an ebb to it. For example, your body temperature peaks and ebbs. You know, the way your hormones are secreted, there's a certain time it peaks and a certain time it ebbs.

And so your circadian rhythms and your hours of wakefulness, which is your sleep drive, they work in concert together to keep you either awake or asleep in the 24-hour period, right? So when we wake up in the morning, our sleep load is really low because we've had a good night of sleep. As the number of hours awake accumulates, you get sleepier and sleepier, and then you fall asleep at night. And then, of course, remember how we talked about circadian alert, alertness varying. So you wake up in the morning, your circadian rhythms keep you awake, but then in the mid-afternoon there's like a slight dip, and then again, you increase. So they sort of work in concert. And what's Dr. Panthers lab, what they do, what they found is

that, you know, we as soon as we wake up, our mouths are open, we start eating and we eat all the way till we go to bed. And of course, we've already established, people don't get enough sleep and the fact that people are sleeping in, you know, random, you know, their circadian, they're not sleeping in alignment or in sync with their circadian rhythms. And, you know, his, his data shows that your stomach and your digestive system needs rest too. And the only way to do that is to restrict the time that you're eating. And, you know, of course he's going to give you a lot more detail about that. But yeah, I recommend. and that quite a bit. And it's actually very, very useful, especially when you're traveling.

So, you know, when I'm working with people and I'm working with jet lag, we talked about that circadian clock and that circadian clock. Of course, light is the light and darkness are the two major zeitgebbers or cues to your circadian clock. But the timing of food and the timing of exercise is also important. And so if you can strategically decide what time to eat and what time to exercise, that can also help shift your clock whenever you're traveling. So just strategically for our listeners, so basically if they want to create as much synchronization with their circadian rhythms, they want to try to anchor their sleep wake timing, their regulate their exercise timing potentially, their meal timing, so really kind of find

a feeding window that's consistent, and that we're staying within that. feeding window. And then finally, really, how we're exposing ourselves to light. So, you know, a lot of light when we want to be alert. No light when we want to be winding down and calm. Right. Now, one of the things we do not talk about is chronotype. And that's important because when we talk about sleeping in sync with your sleep cycle, it's important to be aware of it. Perfect. And if we can talk about this in the context of presenteism, I've actually, you know, heard you talk about, you know, just work schedules and being a night owl versus a morning lark and yeah so if you want to kind of dig into that it would be amazing so one of the functions

one of the very important functions of your circadian clock is also um is something called your chronotype which is your it's like a genetic predisposition that people have to be either morning people or night owls you know people sort of intuitively know you're whether you're a night owl or your morning person or an intermediate and you know there there are there are some really good questionnaires that you can use, clinically validated question as you can use. And, you know, asking people, like, if you had something really important to do, if you could choose whatever time you could do it, what time would you like to do it? And stuff like that sort of help you get, you know, come to know. So the problem, of course, is that the time that we sleep and the time

we wake up isn't really only decided, Kristen, by our sleep need or our chronotype. It's also decided by where we live, what kind of work we do, what time we have to show up to work, you know, whether we have kids, do we have to get them to school on time, you know, do we have to be on a phone call speaking to Asia at a certain time? So all those different things also decided. And because we have all these competing factors, people don't get to bed and don't sleep at the time that they want to. And one of the things actually that happened during COVID is when lockdowns happened

and then people weren't going to places. You know, they were sleeping more in alignment to their own circadian clocks. You know, they would perhaps go to bed late. And, you know, I know that my teenagers were, you know, they would sleep and they didn't have to wake up at an ungodly hour for them. And we saw this in the move data too, you know, obviously hundreds of thousands of folks, right? We were able to see this. Everyone just kind of shifted to their preferred biological preference.

Right, right. And I think one way for your audience to understand this always also is that the clock on the wall, you know, really when it comes to your sleep, you know, may not have that much meaning. And I like to describe it this way. So I'm definitely a morning person. I like to go to bed at, you know, nine, nine, thirty, you know, wake up between four and five. For me, midnight is the middle of the night. In contrast, you know, my youngest daughter, she's a night owl. And if, if allowed, left to her own devices, would like to go to bed at, you know, between 12, 30 and 1 in the morning and sleep in until about, you know, eight or nine. For her midnight is not even the beginning of the night. Yeah, just, you know, I think the way society is set up, it obviously gives preferential treatment, I think, to morning larks, right? You know, you're due at work at a certain time. And, you know, that's just to be really difficult for a lot of folks, you know, and just, you know, we kind of see

night owls, you know, tend to be more at risk, you know, for certain diseases. And, you know, so it's kind of, I just would love to get to a place in our world where, you know, we're actually organizing our shifts at work. And, you know, people are, able to be more aligned with kind of their natural preferences and it just seems almost criminal, right, given what we know. Let me back up here and say that your circadian clock and your chronotype actually profoundly affects your sleep need. What happens is that if you're a night owl, you know, you can get into bed at 10 o'clock. But, you know, 10 o'clock for somebody who doesn't fall asleep because they're a night owl till much later, all that's going to do, you know,

If it takes you two to three hours to actually fall asleep, but you still have to wake up at six, then you're not going to get your sleep need. And the reverse is true too. So if you're a morning person, and that happens with a lot of players, because many of the games are at night. So evenings for players are often very chaotic, they have a game going on, they have other activities that they have to do. So they don't even get to bed on time, but because they're mourning people, they tend to wake up early. And if that happens, then you're not going to make. your sleep need. Yeah. And I think to your point earlier, you know, I think the culture is

starting to change. You know, I think the awareness is, is increasing. And I think people are starting to recognize that, you know, short sleep is not helping productivity. And there's lots of really good data now to actually prove that that's, in fact, the case that productivity actually declines. Right. Right. Right. When you're, you know, at a sync with your circadian rhythm. So, yeah, hopefully there's change coming, you know. Yeah, I was going to say that. And that is, you know, But there are profound health, like we talked about cardiometabolic health, effects of getting less sleep. But this is the culture that we live in, that we have to talk about productivity to get people

to listen. You know, sleep is something deeply personal. It's deeply restorative. It's something that people do in their bedrooms. But people, you know, the only way you can get people's attention is if you talk to them how it affects their productivity the next day. Perhaps then they, you know, they might make an effort to do that. And I think it's also a function of age.

I mean, I remember not hating naps and absolutely love them now. Let's actually, let's talk about age for a second. We know that, you know, a physiological signature of aging is that your sleep gets worse. Does sleep have to get worse as we age? Is there anything that we can do to kind of combat this? Right. So some things naturally do happen. So the amount of deep sleep that you get, uh,

tends to reduce as you get older. And what that means is that, you know, deep sleep, you're more difficult to arouse from deep sleep. I, you know, my teenage son, when he's asleep, you can go and, you know, there could be elephant rampage going on. He's not going to wake up. I'm so jealous that doesn't happen with us, right? But so because your sleep becomes more easily disrupted, you're likely to wake up. There's other things also.

As you get older, especially, you know, after retirement, people. may be napping during the day and then if you nap longer during the day then you don't build up that sleep drive as much they may have to get up to go to the bathroom they may have you know they may they may have aches and pain so there are other factors that might be contributing to poor sleep but poor sleep should not be considered as something that happens with everybody as you get older if people are having poor sleep and as they're getting older it's very important to seek help because they're You know, there's definitely things that can be done to help get their sleep better.

Right, right. And then there's, you know, there's, of course, the obvious stuff in terms of the sleep hygiene. And we talked about the circadian, the anchors, you know, in terms of light exposure at the right times and real timing, exercise, and sleep wake. And perhaps we should take a few minutes. Remember, we didn't talk about that last bit, which is sleep quality. You know, sleep quality is just, you know, it's a little bit difficult to define, but it's basically. the ability to fall asleep within a reasonable amount of time and then stay asleep for 80 to 85% of the time you're in bed and to wake up feeling refreshed. And then all these external

things that you can do during the day and in your bedroom at night that might help you make sure that you get good quality of sleep. So, you know, things like reducing caffeine intake, not drinking alcohol too close to your bedtime, which can, you know, interrupt your sleep or disrupt your, especially your REM sleep. You know, you see that on the whole day. Data. Holy cow. Alcohol is crushing on every level from recovery to obviously to fragment sleep. Right. And then, or, you know, making sure that the bedroom is cold and dark and quiet or, you know, electronic free. You want to, yeah, you know, keep your bedroom for sleep or sex. Those are the only two things you want to be doing in your bedroom. And yeah, yeah, that's,

those are all things that you can do for good sleep habits or sleep hygiene. Yeah, that's great. I wanted to, you know, as we're kind of talking about sleep quality, you know, you kind of mentioned behaviors during the day that are really central. One of the things that, you know, seems to really impact the quality of sleep is the degree to which you accumulate stress throughout the day. And I've heard you talk about worry time. And I, you know, this might be, you know, I think there's obviously a huge connection between sleep and mental health, clearly. And quality sleep is, you know, kind of will really keep you psychologically healthy, right? from everything that you've said. So talk maybe a little bit about, you know, how to mitigate stress during the day with this kind of worry time strategy you have. Right. Sleep and mental health is a bi-directional relationship.

I mean, you know, if poor sleep worsens mental health. Mental health issues are typically associated with poor sleep. And if you don't improve the sleep, mental health doesn't get better. In fact, just recently, I want to say in this last one month, there's this great meta-analysis that came out that showed that improving sleep improved every aspect of mental health. They looked at depression, anxiety, et cetera. You know, substance use, everything got better if you improved the quality of your sleep.

Yeah. So that's number one. That's really important. The second thing I want to, so think about what happens at night. So, you know, sleep is like a reset button and it helps you prepare to face the stresses of the next day. If you don't sleep very well, you're ill-prepared, and if you don't phrase the stress is really well, you know, that tends to make you more anxious and that's going to make you sleep poorly. It's like a vicious cycle. The best way to intervene is to try and improve your sleep. So that's the second point. But third, let's come to, you know, your question. And what happens is that because we live very busy lives, people are on the go all the time. So sometimes when they get into bed, it's the first time they give themselves an opportunity to kind of think about. It's not even consciously that thinking about it is all these like thoughts come crowding in and they're like all stressed out and and then they're or or you know or I was I think I was telling you I just recently was speaking to some a head athletic trainer and NFL team and he's like well you know he gets home it does thing and then he gets into bed and he's like working on his head on his laptop turns it off and he's like well I have to sleep now well that's not how sleep happens it's not going to happen.

Even an aeroplane when it's about to land, it doesn't just like flop from the ground. It's not like going full speed and it's like, you know, that's not like. There's a transition. Yes, there is a transition. You know, it decides it's like circles around, like lowers its altitude, slowly comes down. And you want like a nice, really, really, you know, soft landing. And so think about that building in that landing time for your sleep in preparation of sleep. It's like building a winding down.

And the winding down has to be both physical as well as mental in which you wind down. That's a good point. You know, so perhaps set an alarm. So if you think your bedtime should be 11.30, maybe at 10.45, an alarm that tells you, well, it's time to wind down. And winding down shouldn't. Most actually has that little recommendation. You turn on your notification.

We'll tell you to wind down. Right. You know, maybe a hot bath or a hot shower or some stretching. exercises, you know, spiritual or, you know, meditation practices, reading a book or, you know, something to help you quietly relax so that sleep can happen, allow sleep to happen rather than command it to happen. Yeah. And then, of course, you know, talking back now, settling back to your original question, you know, taking short, regular breaks during the day is really important because otherwise you're going all the time. And, you know, I'm going to tie two things

together you brought up presenteism which is you know being present and work and spacing out you know being on the internet or not being able to focus that's because you know you really can't keep going all the time so for every 90 minutes or of and that again is individual whatever time it takes you can do focused work you do need a few minutes of recovery to happen so that you can sort of be prepared for the next 90 minutes of you know of work and perhaps do something quiet and relaxing in the mid-afternoon when you know you shouldn't be you're incapable of that focus work but also also build a time earlier in the evening where perhaps you sit down with your iPad or with you know a piece of paper or you know maybe perhaps when you're going for a walk

where you you think about or strategize strategize about your next day you know think about your worries think about things that you have to that and that that that which allows you time to actually give it some thought and so that you've done it earlier during the day. Now, it is a practice that takes time. So I don't want to, you know, I don't want people to think that they're going to do it one day and it's going to be, it's going to, you know,

if you've taken years to build bad habits about your sleep, it's going to take your while to build this habit. I mean, patience is definitely a virtue here. You want to, you know, you want to take, time and just to kind of do it and I'll tell you another thing and I find this when it comes to sleep I think it's really important I have to say that I tell this to every head coach or GM that I work with or a CEO I work with is that the buy-in often comes after you've started the behavior you can't really you know if you start say a meditation practice whenever you start any behavior

change you you sort of kind of commit to the behavior change it takes a while you see results that those results happen you know cause changes in your belief system and result in a buy-in and that's when the buy-in happens the behavior the practice sometimes precedes the buy-in sometimes you really have to do something to build that buy-in and sleep and is a perfect example of that. Well, you know, you're telling me to go to bed later and then you're going to do this or you want me to take this 20 minute nap. How am I even supposed to do it? Well, I love that you highlighted just this idea of, you know, short breaks throughout the day to basically prevent that stress accumulation. And I think if people do start there, I actually

I think see an improvement in their ability to fall asleep at night because they're not, you know, if you think about it from an autonomic nervous system perspective, when you're, You're kind of hypervigilant throughout the day. You're activating the synthetic branch of the nervous system. And, you know, as a result, you know, you're, you're just flooding the system with cortisol, adrenaline, and epitaphren. And it's just like there's, it's hard to come down from that, right? But there's many minutes of break, you know, after a 90-minute focus task will allow you

to re-engage your task, I think, with the level of focus, right, to prevent that presenteism talking about it. Yeah. So let's, let's just talk a little bit more about the naps to give people an idea, you know, outdoors is better than indoors when it comes to those breaks not being on the phone or you know electronic free is is better interacting with other people is better you know that you know walking to the water cooler or taking a short walk outside and interacting with people deciding that's the time you want to call your mother or you know is if that's a restful

activity for you yes yeah if that is a restful activity well you know you know those are the ways that you can build short times. And I will tell you that people will give you a pushback and say they're going, they have to go, go, go all the time. And again, I always bring it back to, you know, working longer doesn't equate to working more effectively. Right. And to be effective, you have to build in those breaks into your day.

Our listeners ask a lot about, you know, supplements and, you know, sleep medications. Number one, are there any sleeping pills that can actually produce a naturalistic sleep? So, first of all, I'm a sleep medicine doctor. And I do prescribe... That's why. You're the perfect person asked this question. Yes. I do prescribe medications, and there are people who need sleep medication.

So not to give all sleep medication a bad rep. But, you know, most... In fact, all sleep medications are usually, they're indicated for a short period of time. So, you know, to help you acutely, really, if you are having... issues with sleep, the long-term way of dealing with it would be to do something called cognitive behavioral therapy for insomnia, CBTI, which is a well-studied, you know, well-researched branch in which, you know, you help with sleep issues. So and, and yes, you're right, you know, all sleep, all the sleep medications which cause sedation, they alter

your sleep stages. So they're not, it's not the same thing as natural. sleeping in the wild, like, you know, sleeping without a pill. I would say if you think you need a sleep pill, you need to see a sleep doctor. A lot of our members on the platform indicate that they use magnesium and melatonin. What are your thoughts on those two? The thing about, say, for melatonin, which is, you know, right now over the counter, there are a few things. So it's a normal natural hormone.

It strengthens nighttime physiology, which is sleep for us. And first of all, the American Academy of Sleep Medicine does not. You know, this is not indicated for chronic people who have chronic insomnia. That is not what it helps with. You know, it doesn't really help with poor sleep. You know, there are correct ways of using it. Say, if you were jet-lagged, you're trying to sleep at a different time zone. If you're a night, owler, you're trying to go to bed earlier, et cetera, that would be the reason.

Now, I don't want to give it a bad, you know, it's relatively safe. But it does have some side effects. Also, because it's over-the-counter, you really don't know what you're getting. again I know and magnesium like the data out there is you know it's not compelling a lot of people use it sometimes it helps for people who have you know if they have like cramping and it might just help them sleep but again I always say if you feel compelled to take medications or supplements to help you sleep you want to absolutely explore that you know why I you having poor sleep? And I, you know, you and I discuss this. You know, I may be sleeping poorly

because I have insomnia. I truly have insomnia that, which is difficulty initiating or maintaining sleep. You might be sleeping poorly because it's just not your bedtime. You're biologically, you're wired to go to bed at one in the morning and you're trying to fall asleep at 10. You know, another person, Matt here might be sleeping poorly because he's on the phone and playing video games at night. And, you know, that, and then he's trying to fall asleep, so he's all wound up. And, you know, other people may have, may be sleeping with a loud partner who keeps them awake. So unless you explore the exact reason why somebody is sleeping poorly, you really can't really, you know, a medication is not going to treat any of them. You really want to find out

exactly, which is why, you know, wearing a whoop or something, if that helps, because then you can look at back at the data, you can try to make correlations of what had happened at that night or whatever. Yeah. And then... Can ask better questions. Yes. Yeah.

We just kind of back in, you know, just as a summary, like if we're to look at sleep quality, okay, what are the, what's the most profound behavior we can grasp on to that will help drive sleep quality? And we'll just kind of go down the list here real quick. Things that you do during the day really profoundly affect. So there's many breaks. Right. So during the day you want to be exposed to bright light.

You want to have a schedule. A schedule is really good because it sort of anchors your day. You want to build in short breaks during the day and you want to build in that worry time. And then leading up to the time that you're going to go to sleep, you want to have that winding down schedule that sort of helps you, that prepares you for sleep. But really, three simple things if you do. really will profoundly affect the quality of your sleep. Number one is to be cognizant of how much caffeine you're drinking and how close to your bedtime you're drinking that caffeine.

That really happens. That really is really helpful. Number two is alcohol or nicotine. So alcohol and nicotine, they're both going to disrupt your sleep at night. If you drink it too close to your bedtime or you, you know, if you're chewing tobacco or smoking right before your bedtime, it's going to impair the quality of your sleep. And number three is light.

exposure. And I cannot tell you how important it is because it's really, it's, you know, it's the interactiveness, it's playing video games, you know, and of course with the teams I work with, you know, if there's a, there's a players playing on video games at night, they're playing with other players. So they're not only keeping themselves away, they're keeping other people, other players. Yeah. You know, or reach with your phone in the middle of the night to check the phone and then like going down the rabbit hole of like going on to social media, you know, But those three simple things, if you can please start there, I think that your sleep will be better. Yeah.

And just to double click on the light piece, there's some literature out there that basically says, you know, any light exposure between, and please correct me if this is not accurate, but any light exposure between 11 p.m. and 4 a.m., you actually blunt or mute the release of serotonin next day. Yeah. You know, you have to just be mindful of how much light is being exposed, what you're doing with that light. Yeah, that's how I would put it. You know, and a lot of what you mentioned about quality, I think, applies to consistency. So your ability to actually fall asleep at your preferred

time is very much dictated by the morning light you're getting. Right. And I don't know how much time we have, but that is kind of an important thing. Consistency is important because what people do is, you know, during the weekday, because their sleep time is dictated by their work. So they may go to bed at a certain time or wake up. And then on the weekend, because now they don't have be anywhere. Let's go to bed like four hours later and then sleep in for another, you know, till about noon. And if you do that on a regular basis, that inconsistency itself has significant cardiometabolic effects. And so you want to try to be consistent. Your wake-up time really shouldn't be, shouldn't vary by more than an hour or so. So is there anything that you feel

like we kind of miss that you're like dying to kind of tell our listeners about? I would say that everything improves if you improve sleep. There is not a single thing that doesn't improve with better sleep. It really, really doesn't. You know, your relationships, the way that you function, your interaction with your children, with, you know, other people, the way that you're exercising, the way that you're metabolizing whatever you're taking in. Like, there is nothing that does not improve with better sleep. Well, that seems like a really good place to end. The doctor's saying, can folks find you and the work that you do? So I do have a website, MetaSingmD.com. And then I, yes, I do. I'm on LinkedIn. I'm on Twitter and I'm on Instagram.

And yes, if you can just link those. I think like Twitter is kind of amazing, like all the sleep people that you can interact with. I think LinkedIn is kind of amazing too. Oh, it's amazing. I love following your work on LinkedIn. Yeah. Thank you. And as I do yours. So yeah, yeah, those are the ways to get in touch with me. Thank you. Well, Dr. Singh, it's been such a pleasure. You are just a treasure trove of insight and wisdom. And I know our listeners are going to really appreciate the level of depth that you provided here today. And just thank you for all your good work. Oh my goodness. Thank you. And thank you for giving me a platform. Thank you to Dr. Singh for coming on the WOOP podcast. If you enjoyed this episode of the

podcast, please be sure to leave us a rating or review. Don't forget to subscribe to the Woop podcast. You can check us out on social at Woop at Will Ahmed. And don't forget you get 15% off a W-W-M membership if you use the code, Will, W-I-L-L-O. Okay, folks, that's it for now. We'll be back next week. Stay healthy. Stay in the green. Thank you.