The sleep habit that quietly raises your risk of heart disease | Dr Kristen Knutson

Sleep isn't just about how many hours you get. For decades as a society we've been obsessed over sleep duration. Seven hours, eight hours, maybe nine, as if that number alone determines whether we're healthy. But what if the real story here isn't just how long we sleep? But when we sleep, how consistent we are, and whether our body's internal clocks are actually working in sync. In this episode I'm joined by Dr. Kristen Nutsen, a leading sleep and circadian researcher and chair of the American Heart Association's recent scientific statement on circadian health. We unpack what circadian biology actually is. White sleep is in fact multi-dimensional and how the timing of light food exercise and sleep itself can shape your risk of obesity, type 2 diabetes, hypertension, and cardiovascular disease. We also discuss melatonin supplementation. What it actually does, why it's a timing signal rather than a sleeping pill, and how to think about the correct timing of supplementation if improving sleep onset is the goal. This isn't about sleeping more. It's about sleeping and living at the right time for your biology. Okay, let's get into it. You specialize in sleep and circadian research. How did you find yourself working in this area of science and how would you describe what this field of science is trying to understand? Well with respect to how I ended up here. So my PhD is actually an anthropology and so what I was interested in was understanding how biology and social and cultural factors intersect to impact human health. And both sleep and circadian rhythms, as we'll talk about, they're biological phenomenon, they're critical for health, but they're strongly influenced by behavior, beliefs, cultural practices. So to me sleep and circadian rhythms really seem like an important area of research. It actually goes back to before I went to graduate school. I was a secretary to the chair at Northwestern neurobiology and physiology in the chair at that time was a professor named Fred Turic who studies circadian rhythms. So I actually started learning about it even before I embarked on my PhD. So it was a lesson and you never know where you'll end up or who you'll end up working with in the future. In terms of what we're trying to do is understand how sleep, how circadian rhythms impact health and a variety of health outcomes from cognitive health to mental health to physical health. And importantly, what can we do about it? Like how can we leverage or improve sleep health and circadian health to reduce disease risk or manage disease or improve health and longevity? And how would you describe the current state of of sleep health and circadian health in a country like America? I think unfortunately the advent of electricity and light and the 24/7 society, which is really important in a lot of ways. Certainly we want our hospitals open night and day, but it comes with consequences. And I think we're working now to understand how to mitigate some of those consequences of having a 24/7 society and technology available at all hours of the night and understanding, you know, what are the implications or the consequences and what can we do to prevent the negative consequences? Well, maintaining the positive ones. Before we go further, I've read a bunch of your papers and there's going to be a lot of terms coming up in this conversation like circadian health and circadian disruption. So maybe we define some of those so we're all on the same page as we're talking about and perhaps we could start with circadian health. What does that actually mean by definition? So circadian refers to circa being about in D in a day and refers to the fact that nearly all living organisms have circadian rhythms and these are 24 hour or daily rhythms in a variety of physiological processes, hormones, alertness, body temperature, heart rate, all throughout the body. And the fact that they're found in all nearly all organisms from bacteria to fish to humans shows how important they are. And so circadian health refers to optimal circadian rhythms. And what I mean by that is we have rhythms found in tissues and organs throughout our body including our heart, our muscle, our liver, our brain. And we want all of our rhythms to be synchronized with one another. And we want them to have a nice robust clear rhythm and not be fragmented or irregular. And so optimal circadian health is when all rhythms agree about what time it is and the rhythms are strong. But the disruption then is when this is not the case. Something is disrupting either the synchronization between your internal world and the external time or even within your body. Some rhythms are not aligned with others. Okay, so I'm going to throw this back to you and you tell me if I'm hearing this correctly. But we have these kind of rhythms which dictate how fast our heart's beating or where our blood pressure is at or how alert we are. Our state of a razzle, are we awake or we sleepy? How well equipped we are to metabolize nutrients. And what you're saying is that it's important that these are kind of in sync with one another. Right, because we think the main role of circadian rhythms and why we see it in so many organisms is it's allowing the body to anticipate when sun will rise or sun will set and organize our physiology and these processes in a pro-active matter. So to simply put it to be able to hit the ground running when the sun comes up if you're a diurnal animal. And if they're not organized, then when we eat, when we sleep, when we're active, we want them to all occur at the correct time of day in our different tissues and bodies to expect them at the same time of day. Right, so we don't want our essentially, we don't want to be waking up and getting ready to kind of be in a state of readiness to take on the day, whatever that the environment is going to throw at us, but have our biology in a state that would be associated with sleep. Yes, and so the easiest example I think is internally all my rhythms may be aligned with one another, but if I fly to the other side of the globe, the external world is going to be on a very different time when I first get there. And so I'm not, I'm going to be mismatched and I'm not going to feel good. And you know, we call it jet lag. We all, many of us have experienced that and that is circadian disruption. Fortunately our system eventually can adapt, but initially that is circadian disruption. And that's a very, that's a very acute circadian disruption that you feel, you know, immediately and most of us have experienced, but what you're saying is there can be a more kind of innocuous subtle chronic disruption to those circadian rhythms. Yes, even there's a term called social jet lag. So what I describe is travel jet lag. Social jet lag is when on days off, you're going to bed at a different time and active and eating at a different time than you do on your work days or school days. And so even though you're not actually going anywhere, you're still in say Chicago, like me, you're changing time zones, you're changing times in your irregular in your behavior. And that is makes it very difficult for your internal clogs to synchronize when it's uncertain, when are you going to go to bed tonight? When are you going to eat? I don't, you know, like it's not being regular in your timing, even if you don't leave your city is going to have an impact on how well your circadian system can synchronize. And you use the kind of wording that you're not going to feel as good, but you were and your team were compelled enough to write this new AHA scientific statement on the role of circadian health and cardiometabolic health and disease risks. So it's more than just not feeling good what you're saying is that when you have this disruption, like you were just explained that we're actually increasing our risk of developing cardiometabolic disease. Correct. It's not just a mood issue. It's and it's not temporary unless unless the irregularities temporary. Long term circadian disruption if our circadian health is impaired in any way seems to be associated with disease risk and you know to give you an example with blood pressure, which you brought up earlier, there is a 24 hour rhythm and blood pressure. It's supposed to it's highest in the morning and stays fairly high during the day and it's supposed to dip around bedtime and stay low when you sleep and then go back up. Dipping during the night is considered healthy and people who don't dip during the night are more likely to develop heart disease. And circadian disruption if you don't have a good rhythm of that blood pressure will be associated with less dipping and that we know is a problem because the blood pressure we want the blood pressure to go down at night. And so that's just one example of one rhythm and we expect similar issues. If the rhythm isn't operating in a way that it should, then there can be consequences. And do we understand if the the rhythm becoming disrupted is causing the disease state or if the rhythm is disrupted because of the disease state? No that's a great question. I suspect it does go both ways but the evidence showing that circadian disruption can lead to the disease are based on more experimental studies either in animals or even in humans where the circadian rhythm is disrupted. And then these more short term risk factors for heart disease or other conditions change in a negative way. So for example in humans who have to undergo this complicated experimental study where the rhythms are disrupted you might see their blood pressure higher. They might recover hopefully after the experiment but if that is a persistent chronic behavior then the blood pressure may stay elevated or to continue to increase which could ultimately lead to hypertension. And so these experimental studies suggest that there is biological plausibility, if you will, linking circadian disruption to the development of impairments in health. And what are the main things that a thought to contribute to that circadian disruption in the first place? So the main signal or time queue that our internal clocks use to synchronize with the external world is light. So light enters through the eye and goes to what we call the central clock in our brains to synchronize our and then that central clock is supposed to help synchronize all the internal clocks. If we are exposing ourselves to light at the wrong time of day, like when in the nighttime, it tricks the brain into thinking it's still daytime. And so we know if we're up past sunset, which we often are, especially in the wintertime, that we're exposing ourselves to light if we're awake usually, whether it's on our screens or our overhead lights. And so this light exposure at inappropriate circadian times can cause circadian disruption, especially and then this comes back to the regularity. So if your sleep timing is irregular, that means your awake time is also irregular and your light exposure will be irregular and it makes it difficult for our circadian system to stay synchronized and have regular rhythms from day to day. So light is a big one. And is light exposure a greater influence than things like meal timing and exercise timing? So light from experiments light has the is the strongest signal to change the central clock that I described. Meal timing, it's like, you know, there are there are timing signals that some of our peripheral clocks like in our guts, in our liver, in our muscle, use to synchronize their rhythms as well. So in a person who's completely synchronized, perfect circadian health, they're eating during their biological daytime. They're not eating during their biological nighttime. But if somebody is eating during their biological night, when the central clock thinks they should be sleeping, that could confuse rhythms and say your liver or your pancreas or your muscle into thinking it's a different time of day than your brain thinks it is because things signals from eating such as glucose levels going up or the metabolites from eating itself, the nutrients themselves might serve as a signal to these other clocks indicating it's actually still daytime. And so that's how a peripheral clock in the central clock can become dis synchronized with one another and disruption can occur internally. So it depends on which part of the body we're talking about and the clocks in those different parts the body, there are different signals that can re-synchronize or synchronize them differently than just light and just the central clock. I've been using Woop for over six years and I can confidently say it keeps me on track when it comes to my sleep and exercise routines. The next generation of Woop isn't just tracking your workouts, it's monitoring your sleep quality, your recovery state and even giving you insights into your biological age, no screen, no distractions, just continuous data on what your body actually needs. And here's what matters, daily Woop where is linked to increased physical activity, to better sleep and improved heart rate variability. I have no doubt that my Woop is helping me train smarter, recover faster and make decisions that support my long term health. Head to join.woop.com/simon. That's join.woop.com/simon to get one month off your first subscription. Okay, so let's stay on this this idea for a moment that there is actually more than one clock. There's not just a central clock in the brain that's controlling all of these rhythms. Can you can you further explain that so we can kind of appreciate circadian biology a little bit more broadly? Yeah, no, and that's an important point. I think for a long time in circadian science, it was thought that this central clock in the brain was the only clock and it was responsible for all the rhythms found throughout the body. But then, you know, a decade or more ago, now it was discovered that actually the molecular clock, which is, you know, genes and proteins that control these rhythms actually exist throughout the body. So in the pancreas, in the heart, in the muscle. So the molecular machinery, if you will, that are regulating rhythms in these specific organs or tissues exist and operate somewhat independently of the central clock in the brain. Ideally, they're all synchronized and agree with each other, but they the peripheral clocks, these exo- those clocks in different parts of the body can become synchronized by separate signals separate from the central clock. And that's why they can become de-synchronized with one another, disagree about what time it is. And that leads to this internal circadian disruption. You mentioned genes in. And a question that I had for you here was around differences between people and these rhythms. And kind of a word that comes up a lot in in the research in your papers is this idea of chronotype. Yeah. What do we need to understand about chronotype in order to then understand, you know, how light exposure or time of sleep or time of eating might differ between individuals. So chronotype, like you alluded, refers to an individual's time of day preference. So we've heard of night owls versus morning people versus somewhere in the middle afternoon people. And this is your chronotype. When what time of day do you find as easy as to sleep? What time of day are you best performing at work or writing or reading or exercising? That refers to an individual's chronotype and there is variation among people. We also change as we age when we're younger, when we're teenagers, if anyone's ever known a teenager, they stay up late. They are night owls. They are delayed chronotypes. But as we get older, we slowly advance. So we know that people who are much older often get sleepy much earlier than the day and they wake up really early. So that is a biological phenomenon that our chronotype tends to get earlier and earlier as we age. What this means is that the timing of the rhythms are just either earlier or later than others. It doesn't mean that they don't have rhythms if you're a night owl versus a morning person. It just means that, say, peak alertness is occurring later in the day for night owl than is for a morning person. This makes it challenging when someone asks me, what time should I eat breakfast? What time should I go to bed? And it's like, I can't answer that without knowing internally what time your clock is set at. Also, I would say chronotypes we believe are somewhat driven by genetics. We'll say around 50%. So if your father's a night owl, there's a good chance you'll be a night owl as well. But it also means that about 50% is not genetically driven. And there are behavioral factors that can be leveraged to try to work with individuals who want to change the timing of their behaviors. But and we can dig into that a little bit more when we want to think about interventions to improve circadian health. But a lot of what we're talking about is going to be relative to one's own internal clock timing, their chronotype, rather than the clock on your phone or on the wall. When you say someone's circadian rhythm is advanced. If they're not. So if someone is a night owl there circadian rhythm is delayed. Yes. Which means that they if we're talking about the different rhythms, are we mostly speaking here when it comes to sleep, wake cycle to the rhythm of melatonin and cortisol? Yeah, melatonin cortisol are both really good markers of the central clock's timing. And how does someone understand what their chronotype is? Because if I use myself as an example here, I feel my best when I go to bed at like 9 or 10 p.m. and wake up, you know, before 6 a.m. I did a genetic test and I don't know how accurate this is and it's with the company that I'm not affiliated with. That doesn't matter. But it came back and said based on these, you know, I think it was like 10 or 15 genes that I'm a night owl. And so when I got those results, my question was, have I at sort of just sort of behavior and, you know, work need to be up early? I don't have kids, but I imagine many people who do need to wake up early. Have I just kind of drifted to this kind of going to bed early, waking up early, way of living, which might actually not be optimal for me and best aligned with my genes. And so I wondered, like, at an individual level, how would I actually determine that? Well, I think your these genetic screens are going based on probabilities and it is not for certain that you are meant to be a night owl. The way an individual can try to determine a night owl or morning person with one of the way that some of these large observational studies do it is a single question. Like people tend to know how the time of day they prefer. There's a longer version of the questionnaire, which is called the horn osperger, the morning-ness evening-ness questionnaire. If you're really driven to fill one of these things out and see what the questionnaire says, the way to objectively measure it now becomes more challenging. And I think this is one of the challenges for our field scientific and research field is, or clinically even, to be able to measure a person's internal clock timing. It's really challenging to do right now. I'm hoping some day technology will get us closer to where we can determine this. The most, you know, what we call the gold standard is called the dim light melatonin on the So, melatonin, which you mentioned earlier, is a hormone that's produced by our body and it's considered a chemical signal of darkness. So, it's not, we don't produce it or secrete it when it's bright out. And when it starts to be produced assuming it's dark enough is based on our internal clock. So it is a marker of what time the internal central clock thinks it is, but it'll only be able to measure it if it's dim or dark when you're measuring it. So you might already figure out that the challenge then is we have to collect, say, saliva samples for five, six hours before you usually go to bed, in dim to dark light. And that's not something that's simple to do. It is what circadian clinics do when they're trying to ascertain whether people with a circadian disorder are actually delayed internally or not. And so it can be done, but it's not something to easily do at a consumer level very well. And I'm hoping to improve that. But right now measuring our internal clock timing is a really difficult thing to do. Do you think we have a good idea as to what percentage of the general population are nine hours? So as I said, it depends on what age group we're looking at. In a study, I was part of that use the large data set from the UK, which I wouldn't imagine is much different than the United States in terms of prevalence. The youngest age in this study was 37. So younger people are not part of that. And the proportion of individuals saying they were definitely an evening type was about 9%. So say 9%, 10% of the population. But again, it's going to be much more if you're looking at teenagers or even young adults. And that number goes down as we start to look at older age groups. So it's not an insignificant number of people. I ask that question because I do think society is certainly set up in a certain way, which means a lot of people probably go to bed between 9 and 10 or around 10 so that they can get up early enough to get their workout in, feed their kids, do all the things before they go to work, which starts at 8.30 or 9. And I was wondering if maybe that's an explanation for why sometimes you speak to someone and they say, I feel awesome and I only get six hours of sleep a night. That's all I need. And then someone else is like, I get 9 hours and I feel really tired. And I was wondering if that's because that person who's getting six is sleeping at a time, bed is suited to the chrono type. Yeah, that's a good point. And we've talked in the past. You mentioned it earlier on, I think, like sleep health. And then this recent statement was on circadian health. And we wanted to, you know, one of the goals was to make it clear that circadian health and sleep health are not the same thing, but they overlap. And what you're mentioning is a key component of the circadian system. One of its roles is regulating sleep wake. So it's very difficult to fall asleep in the middle of the, well, you know, 4 or 5, 6 p.m. if you're just going to bed at 9 or 10, unless you're really sleep deprived. And so the so sleeping at the correct time of day will result in better quality sleep. And so I think the person who's getting six hours in bed at the correct time of day is going to have better quality sleep than the person who's getting six, seven hours of sleep at the wrong time of day, like maybe in the middle of the day, daytime hours. I do as a side want to point out that there was a study that looked at in a study at that intentionally sleep deprived people, think allowed them 4 hours in bed. And ask them, how are you feeling? We had a range of people like I'm fine, too. I'm miserable. But there was no relationship between how they said they felt and how well they performed on cognitive tests. So people may not necessarily be a good judge of how sleep deprived they are. And that is that is also another challenge to recognize. You may think you're okay, but maybe you're just used to not feeling well if you don't sleep enough on a regular basis. In the AHA scientific statement, there's a quote that says, so much about health is focused on what we do and how we do it. But when we do those things matters greatly. I just want to underscore this point for everyone. Can you paint a picture for us? How someone can be seemingly doing everything right from a, they're getting eight hours of sleep that we've been told, that's healthy sleep. Doing the exercise and eating the healthy diet, but still be putting themselves at increased risk of cardiometabolic disease if the timing of those things is not right. Right. So, I think an important aspect of timing is, you know, you should be doing nighttime things at night and daytime things during the day. So you should be eating at night, for example. Ideally, you're not sleeping during the day. I recognize some people don't have a choice if you're a shift worker and we can talk about that. So, regularity, are you getting eight hours a night, but you're jumping all around the clock? Same with meal timing, are you sometimes eating at night, but not at others, even though you're eating the appropriate healthy amount of calories and your nutrients are all, you know, well distributed. So, not only the specific time of day, but how regular you are from day to day is really important to consider for all of these healthy lifestyle behaviors. A light. How important is morning light? So, getting some form of light exposure after waking up versus evening nighttime light exposure. So, we think morning light is the most important light for keeping your central clock synchronized with the light dark cycle, the sunrise sunset where you live. That is a key signal that keeps your rhythm synchronized because unfortunately for most, even though the, we'll say, the rhythm of the earth rotates approximately is 24 hours. And our internal clocks are not all have this perfect 24 hour pattern. We have to keep resynchronizing every morning. And the morning light is critical for doing that. Evening light, on the other hand, if you expose yourself to light at night, particularly early in the evening, that's tricking your brain into thinking the sun is still up. And so, it ends up delaying your rhythms rather than keeping them advanced and aligned with sunset. So, morning light is really good. Evening light is bad. So, this is also about time. It's not that light is bad across the board or good. It matters when you're exposing yourself to bright light. And when you say morning light is good, is it enough to just kind of turn the lights on in the kitchen or are you talking about getting outside if providing it's light outside and to kind of being exposed to natural light? Is there a difference? The natural light is great. It's brighter. It's tones and spectra are the natural light that we all evolve to. Our circadian systems has evolved to work with. Artificial light, if it's bright enough, can have the same effect, which is why light at night, which is typically artificial, can still delay the clock. So, if you are exposed to bright light in your office or in your home early in the morning, it's still going to have the same effect as long as it's bright enough and not kept really dim. If you can see well enough to make your breakfast, that's probably bright enough. You know that moment when you open the trash and you get hit with that awful smell? That's food waste. Old scraps, leftovers, soggy produce, just sitting there. 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Visit functionhealth.com/simonhill and use gift code "Simon25" for a $25 credit towards your membership. What do you think about, and I think these have become popular in parts of the world, where people wake up the morning and still pitch black outside, and there are these kind of artificial light panels that provide certain amount of locks of light intensity. Are those things helpful? Yeah, those are what have been used for people with circadian rhythm disorders, where you're trying to advance their rhythm if they're too delayed. They are beneficial and work to. synchronize your clock. However, the caveat I want to bring up is the issue of chronotype that I mentioned before. So if you typically go to bed really late, say 2 3 a.m. and wake up 8 9 10 a.m. and you want to go to start going to bed earlier, you want to advance your clock, you should not get up the next very next day and start using this light device at 6 7 a.m. Because even though it's early, it's a nice early start of the day for someone who's a morning person to you, that's going to be the middle of your night and that's actually couldn't make things worse, not better. So it's, as you try to use light morning light treatment, you need to do it gradually, you shouldn't like, you should go by what you are habitually waking up now and gradually do it earlier because you don't want to accidentally expose yourself to light at a time of day that will make your clock delay even further rather than advance. So what you're saying is if someone was going to bed at 2 a.m. and let's say that they were waking up at 9 a.m. They wouldn't just wake up early at 9 a.m. and expose themselves to that light that would wake up at 9 a.m. and get that light exposure. And then you can gradually make that earlier. But I wouldn't wake up at 6 a.m. on the first day and start exposing yourself to light because that may be too early and still in the middle of the night. I think that is a challenge when working with individuals is to understand what is the right time of day and circadian physicians of which there are some. They work really hard with patients to understand what is the best time of day for you to get exposed to morning light. Those light panels potentially helpful for shift workers. They are going to be helpful for anyone that wants to shift their clocks. I think the challenge a lot of shift workers have, particularly rotating shift workers, is they're not always working the same shift. And even permanent night shift workers when they have a day off, they tend to want to see friends and family. And so they're awake during the day and trying to sleep at night. So their clock time is shifting back and forth. So using light to try to shift your rhythms, it may not, it may shift it right when it's time for you to go off shift. So shift workers have a unique challenge because they're often awake completely at the wrong time of day and trying to sleep completely at the wrong time of day. Wake all night trying to sleep during the day. And there is a whole field of science and investigators working on a variety of interventions to help mitigate the consequences of a shift being a shift work because shift work has been identified as a carcinogen. And it's linked to cardiovascular diseases as well, like diabetes and hypertension. So manipulating when they eat and when they exercise and trying to make the most of the sleep when they're sleeping during the day are all the different ways people are trying to make mitigate the consequences of being a shift worker because we're not going to, we need shift workers. So we have to try to make sure we maintain their health. Yeah. I mean, now society relies on them and many of them, their heroes like nurses and firefighters and police officers. Is that research has that born out anything yet that we, if someone's listening in their shift worker and they'll like right, it's considered a carcinogen. Are there any, well, I mean, that's the fact and and that's, it's good that there's research looking into this both understanding how it affects outcomes, but then also what can we do about it? Are there any useful tools that are kind of rooted in evidence that people could use that might help them? Some of the work, this isn't work I've done. So I hope I do it justice. But you know, people are looking at, for example, at manipulating meal timing to right before shift and at the end of shift and void eating during the shift because that's the peak biological night. Obviously, you want to eat enough that you're not, you know, really hungry or, or, you know, have high-pig like C-Megavents. But if you can manipulate when you're eating to minimize the circadian disruption by eating the middle biological night, there are interventions related to that that, I mean, I'm sure it'd be easy to find if you searched. And then this is probably on the obvious side, but when you're sleeping to make your room as dark and quiet as possible, which is more of a challenge when you're sleeping in the middle of the day, when the sun is up and everybody else is up, making a lot of noise, but trying to find ways, whether it's ear plugs or eye masks or what you have you like to try to make it as dark and quiet as possible. And the reason I asked about why, at least where my mind was going with that was, okay, during the day, they're blocking out their room and they're sleeping. A shift worker who works overnight. And overnight, I know I know I know totally people have messaged me and I asked, well, should I wear blue, why blocking glasses while they're working in whatever environment is overnight. And I was thinking, well, I can't be healthy not to get any light the whole day. Surely they still want some light exposure and overnight when there's no sun is actually getting some bright light more beneficial than just blocking out light for 24 hours. Yeah, I don't know the answer to that because you're right, is exposure to no light better than exposure to light at night when you're working shifts. I mean, obviously we also, if you depend on your job, you need to have light on for safety, you should. But, you know, otherwise, I'm not aware of studies that I'm not saying they don't exist. I'm not aware of studies that have really examined whether it's better to have dim or blue blocking glasses than to be exposed to bright light at night. And it's going to vary by shift, I imagine too. What about people that are working ordinary hours? And in the evening, you were referring to kind of light exposure before as something which could could cause circadian disruption. If you're getting too much bright light exposure before going to bed, a blue light blocking glass is helpful for that. If they work properly, they should be because our circadian clock that I mentioned that is primarily synchronized where light is the biggest synchronizer. It's really the blue green spectrum of light that has the biggest effect on synchronizing the clock and affecting the timing of its rhythm. So if you're able to eliminate those wavelengths, then that would help reduce the effect of light on the circadian system. Of course, you're still awake. So if the sleep side of me wants you to still go to bed, but if you're awake and staring at your screen and you have to, then that might help if the glasses are the screen or whatever you're using is indeed blocking out these spectra. How do you feel about turning on red lights using red lights in the home instead of kind of ordinary artificial light? Well, it's related to the same phenomenon. That is the blue green wavelengths that are affecting the circadian system and not the red. And so red light is not going to have the same effect on circadian rhythms synchronization that the blue green or white, which is really just a combination of all these different colored wavelengths. So if you are only using red light, it will minimize how much circadian disruption occurs because you're not using the wavelength that has the biggest effect on the circadian system. I don't know, I won't say it has no effect, but it is based on experimental studies I've seen is a smaller effect than the blue green spectrum seems to have. Speaking of night routine, a lot of people are taking melatonin. What are your thoughts on that? And if we are getting a sufficient, appropriate light exposure early in the morning, which to my understanding kind of anchors or sets up that melatonin rhythm later in the day is supplemental melatonin necessary. So melatonin as I mentioned is a strong circadian signal of what's going on the central clock. But if you for some reason are not secreting enough melatonin naturally, then supplementation could have beneficial effects. An example, again, would be jet lag traveling across time zones. I know individuals who use melatonin to try to trick their body into thinking it's later in the day that it is so they can go to sleep at the local time. But if you're not traveling and you are secreting enough melatonin, it's not going to have as big of a fact of any effect on your circadian system. If you're already secreting it and adding more, isn't going to have a bigger effect. However, I also want to point out that there have been a couple of studies that have tested these different supplements and there's widely different amounts of actual melatonin in many of these capsules. And so in part of the issue is although it's regulated as a supplement, it's not regulated as a drug. So there's not as much oversight in terms of making sure that a 1 milligram pill of melatonin is actually 1 milligrams of melatonin. So I urge caution, because once you've taken melatonin, that increases your insulin resistance. And so if you're at risk of metabolic disorders, don't eat after you've taken it. So we need to be careful before we take melatonin, unless we're sure it's a situation that warrants it. Yeah, for that reason that you just pointed out that the supplement industry is very under-regulated. I tend to look for supplements. I'm not sure if you've seen this certification NSF certification for sport. It's like it's a logo and I don't even know if there's a brand that makes melatonin with that. But it's the certification that if you're an MBA player or an MLB or a PGA pro golfer, they only use supplements with that certification because every batch and this is in supplements is tested for the actual active in the right dose and nothing else. I'd have to go out and look and see if there's a melatonin supplement that's done that. But anyway, people can search that as well. I was also interested when I was reading about melatonin to learn that if you are going to take it, the optimal kind of time would be around a couple hours before bed, which I think that's different to how most people take it. Well, so the natural rhythm of melatonin is supposed to increase one to two hours before your habitual bedtime if you're a nice regular and you have perfect circadian rhythms. It's not something you take right at bedtime. It's not a sleep aid. That's a big, that's I think an important thing to keep in mind. It's a circadian medicine. It's circadian medicine. It's not sleep medicine per se because it's a circadian signal. It comes back to the circadian system and sleep being closely related and the circadian system helping to regulate when you can sleep. So they're not unrelated, but it's not a hypnotic. It doesn't make you fall asleep. The same way many sleep aids do. It's a circadian signal to tell your brain, "Hey, night time's coming. Let's get ready to go to sleep." I think that will be used to a lot of people and is an easy switch for people to make because I'm sure a lot of people are taking it as a sleep aid and are taking it right before they go to bed. And then they're like, "Why is it this working?" We have to wait a couple hours. Yeah. Okay. I have more questions about sleep, but as you said, it overlaps with circadian health, but it's also distinct. So let's put a pin in that. And then I want to finish discussing timing by covering male timing and exercise timing in a little bit more detail and we'll circle back to sleep health more generally. Coming back to the timing of food, does the timing that we're eating food matter independently of calories and how much we eat? There's evidence to suggest yes. And one of the first studies that really, to me and to others highlighted that this was an issue. It was an animal study so bear with me, but in mice, they were given food as much to eat either the correct time of day for them, which is actually nighttime because they're nocturnal or the wrong time of day, which is daytime. And then they measured the real wanting activity and they measured how much the animals ate and there was no difference in how much was consumed in these animals or how much they were running on their wheel. But the mice that were eating at the wrong time of day gained so much more weight and the mice that were eating at the right time of day. And it couldn't be explained, like I said, by physical activity, at least on the running wheel and food consumption. So it really suggested that eating the wrong time of day when the body is not expecting it, does not process it as efficiently, it ended up being stored as fat, more than being metabolized. In humans, which is what I care most about, there's also evidence that time of day matters. There was a study in Spain and it was a weight loss study in women. But after they did the study, someone looked at timing of eating and so they just split the women into those who ate after the median for what time ate lunch because we remember in Spain lunches, they're big meal. And before the median, like the midpoint of timing, and it was something late, too, it was like 2pm or something because it's spain. And they just, just doing that simple split into those who ate lunch late versus those who ate lunch earlier, the women who ate earlier lost more weight in this weight loss study than the women who ate later. And there was no observable difference in how much they ate in the groups or their sleep. So something about timing of what you eat, not just the amount or the quality or the nutrients seems to be important. And other work that I've done and others really seems to emphasize the importance of eating earlier in the day. And so just to kind of throw that back to you, what you're saying is that the timing isn't necessarily affecting how many calories someone's eating, how much food they're putting into their mouth and ultimately the amount of energy available to their body. But more so the other side of kind of this energy balance equation that dictates whether you maintain weight or gain weight or lose weight is how much energy the body is metabolizing actually using. That's what we think because that's the missing piece in that animal study I mentioned. It's like, well, they weren't eating more and they weren't running on the wheel less. So why did they gain so much more weight? And the remaining piece of that energy balance is either energy expenditure at rest or even the how much they expanded while running as well as how the body when you eat food is it being metabolized right away is it being stored is it being converted to fat seem to favor storing it rather than burning it because it was eating it in the wrong type of day. And the body is like, whoa, what's going on? This is a wrong time of day for me. And so we think timing matters right now again because it's going to vary about chronotype avoid eating at night, avoid eating within a few hours of bedtime and don't start eating until you get up, but then start eating that seems to be the timing we can say with certainty right now because of the chronotype. Don't eat at night. Don't eat during the nighttime because your body's not going to be able to handle it as well. I'm leaving shift works out of this for people who have to be up all night long, but but for those of us who work more traditional schedules eating at night is not considered to be beneficial. So the best heuristic there, which applies to anyone no matter what chronotype they are is that don't try to avoid eating a couple of hours before you go to bed. Yes. Right. And that time might look different like when you that could be seven camp for someone or it could be 10 p.m. for someone else. Exactly. The flip side of that is eating earlier now. This is a challenge because many people are breakfast skippers and that could be a time issue like they have to get to work really fast. It could be a chronotype issue so people who have to wake up early for work, but it's not a good time for them to wake up may not be hungry yet because it's the middle of their night still. But the evidence suggests that you should eat earlier in the day, at least relative to when you would normally wake up. And we're still working on that because I think that might constitute a novel intervention to understand how meal timing might benefit people. We do a lot of research to say, oh, look at all the bad things that happen when we do this. We switch to understanding what can we do to help people be healthier and thinking about timing of meals and distribution of calories across the day and understand regardless of what you're eating. That's important to it. Regardless of that, understanding how the timing of day can be leveraged to maximize your metabolic and cardiovascular health, I think is an area. When you're starting a new business, you are wearing a lot of hats. You are finance, you are marketing, you are operations, you are logistics and customer service all at once. Finding the right e-commerce solution that actually makes your life easier and takes some of that heavy lifting of your plate is absolutely key so you can focus on growing the business instead of managing tech. 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And when you say eating earlier in the day and you may have said this, are you talking about eating as soon as you roll out of bed? 30 minutes after rolling out of bed and hour after rolling out of bed? Two hours. Well, if you're rolling out of bed at a time that's fairly close to when you want to be from a circadian perspective rolling out of bed, then I would do it. I mean, it doesn't have to be like, you don't have to have breakfast ready to go at the side of your bed. But you know, within 30 minutes is a good idea. Earlier is better. Unless, like I said, you're waking up really early because your alarm's going off and you have to get to work, but it's really still the middle of your night and you're still half asleep, then you might not want to eat for a little bit. This is the challenge for us in my field for advising clinicians, advising people, understanding chronotype and figuring out how do we determine when should you have breakfast, when should I have breakfast, because it's not going to be 7 a.m. for everybody. And that is a challenge. But if it's based on your habitual wake time, then you should be safe in terms of being able to eat during a time your clock is okay with you eating. That makes sense. Does this give you pause when you think about the kind of 16, 8-intimidant fasting that a lot of people practice where, like you said before, I think a lot of people find that 16, 8 fasting easiest when they just skip breakfast. First meal is kind of 12 o'clock, you know, a round lunch time at work. They come home and they can still have dinner with their family. So it's like a socially acceptable way of doing intermittent fasting. Whereas what I'm hearing from you is that a circadian kind of optimal, intermittent fasting protocol would flip that and would be 8 a.m. to 4 p.m., 5 p.m. let's say whatever it is, which it would be more aligned with your circadian rhythms, but perhaps harder from a social perspective. And I think that's the challenge. You're absolutely right. There has been at least one or more studies that have compared early time restricted eating to later time restricted eating. So still the same duration eating window and the early time restricted eating group faired better had better health at the end than the late time restricted eating group. That said, I have heard what you just mentioned that for many people, the late time restricted eating window is much easier to adhere to than the early one. And so if you're not going to do it because it's early than that, I'm going to say that certain negates any benefit of time or certain eating. If you can't follow time or certain eating 'cause we're telling you you should get up and eat right away and stop at four or whatever time. So with any lifestyle intervention, there's all these pieces and components that make it complex and you need to figure out the best way for you to adhere to as many of them as possible. And so I do acknowledge that up front for many people, what I'm saying is the optimal pattern is not gonna work very well for individuals. So I do wanna put that out there that I recognize for many people eating a big breakfast, part in the pun will not go down well. Like it's not going to work well for everybody, even if the science says that ideally that's the pattern we should all be following. - Right, we're talking in kind of generalizations here and also we're looking at the science through the lens of what I'm just to metabolism, not necessarily appreciating society and behavior and family dynamics and all those sorts of things. But I still think it's helpful for people to understand and then apply in your own life and see how you respond and see what you can sustain and feels good and doesn't feel overly restricted. - Yeah, we know what a healthy diet is supposed to look like and we all aspire to eat like that. And we do as many of the things we can, but life is life and sometimes we can't adhere 100% 100% of the time. And so I think knowing what the goal is, is even a great first step. - And if you're finding yourself overly stressed out about all this is probably defeating the entire purpose. - We're not trying to be like, well I give up on all of it. Like if I can't do it exactly like I'm recommending it. Any little bit helps I think. - Okay, I mean what I heard here is trying to not be food couple hours before you're going to bed and where possible eating more of your calories earlier in the day rather than later and those are kind of two good starting principles to work with your biology. All this and I'm not sure if this is something you've looked at or if there's an area of science looking at this. But this clearly a strong relationship, symbiotic relationship between our microbiome, 30-8 trillion microbes and our own health. Does our microbiome have its own circadian rhythms and is that something that you've kind of looked into and does that intersect with food and what we're discussing here? - Yes, absolutely. That microbiome does have its own circadian rhythms and there are people out there who study exactly that. I'm not one of them, but I've spoken to them. And eating at the wrong time of day is going to also disturb their circadian rhythms. And so I know we keep adding layer upon layer of complexity, but meal timing affects, in addition to affecting the synchronization of our internal rhythms, is going to affect the rhythms of the microbiome, which in turn can have effects on our health as well. And so it just re-emphasizes the importance of not only what you eat and how much you eat, but when you eat it. And also even keeping it as regular as possible from day to day. A lot of people eat breakfast at seven, one day and 11 the next and just trying to keep it as regular. Not just sleep regularity, but meal regularity, maybe beneficial as well. - Okay, the third cue or zite was a zite guy, right? - Zite Gaber, yeah, if you have your German word for science, it's time giver. - Time giver. So it was light exposure than meal timing and now exercise timing. So how does exercise act as a signal to the circadian system? - So it can also be a zite Gaber, which is a synchronizing signal to the central clock and to some of the peripheral clocks as well. There hasn't been as much research in this area as certainly for light, for example, but what there has been has been somewhat mixed, but exercising at certain times of day can affect the timing of your clocks. The signal isn't nearly as strong as light. So the effect, how much you might shift your clock will be smaller than a light exposure at the same time or a light exposure would. So it can have an effect, but the effects, we don't think are nearly as strong of a signal as light. Light is definitely still the strongest signal. And then what evidence there is also suggests there might be differences in how much exercise affects your clock based on how old you are. There might be differences between men and women. That still remains to be seen. And so I think we still need to understand how exercise is affecting your circadian clock. And then the question I get a lot and I don't have an answer for is what time of day should I be exercising? Right now I'd say just don't try to exercise right before you want to fall asleep because it isn't a learning behavior. But any exercise otherwise is still better than none. So I'm not going to discourage someone from exercising at certain times of day if that's the only time of day they can exercise. - I know personally that if I'm doing like an intense cardiovascular kind of workout, like playing pedale or something off to 7 p.m. It definitely pushes back the time where I fall asleep. - It's good for sleep. I give you exercise, your sleep quality will be better once you get to sleep. But doing it, giving yourself a nice cool down resting period between when you've exercised and when you want to fall asleep is really important. - Do I read correctly that morning locks are maybe a little bit more sensitive to that, that late kind of evening exercise might affect their sleep or at least the time they fall asleep more than a night out? - It could, especially if by late we're basing on a clock on the wall because it's too a night out, it's not really late. And so many of the associations we talk about differ between someone who's a morning person and someone who's a night out. In part, not to get too much in the nitty gritty of the biology, but in part because there are differences in how sensitive the clock is to different signals. So even light can have a different effect on some individuals versus another. Certainly if you're completely blind, then light is not going to reach the brain to have a to effect. But even without blindness, there are some individuals whose sensitivity to light is reduced and isn't triggering the pathways as strongly as others. And that sensitivity can also be different depending on whether you're talking about nighttime or morning. So again, more complexity, depending on your chronotype and your biology, these different time signals may have different effects between individuals because of that. I think you just need to figure that out. I wonder if that light sensitivity is kind of overcome or corrected by the use of corrective contact lenses or classes? Well, it depends on what if you're over sensitive, then something that might block it might be beneficial. But some individuals may be too insensitive. The light isn't having a strong enough effect and then blocking it or affecting the path through which the light passes isn't going to affect and help them if it's an issue of not being sensitive enough. OK, so what's the take home message for the listener today with respect to exercise timing? What do you want to leave them with? Don't exercise too close to bedtime. Much like eating, exercising eating should be done in the daytime and sleeping at night. So as long as you're-- we want to exercise. Exercise is important. So exercising during the daytime is ideal. It'll help with sleep. The time of day, at this point, we don't have a recommendation to say, oh, exercise in the morning is better than afternoon. Other than, as we discussed, don't exercise too close to bed if you need to get to bed at a certain time because your bedtime will get delayed. OK, I want to explore sleep a little more with you. And you wrote a separate AHA, scientific statement on the multi-dimensional sleep health. We've been trained as a society that eight hours sleep per night equals good sleep, great sleep. That's the kind of north star. Has that ever truly been rooted in science? And do you think we need to be thinking about sleep differently? So there's a lot of focus on how much sleep people get because that was something we've had information on for a while. Like they've been asking the question in these large studies for decades, how much sleep do you usually get at night? But this most recent AHA statement was to point out that sleep health isn't just about how much sleep are you getting. There's a lot more to it than that. I will say the eight hours, most of the studies I've seen seem to land that's between seven and eight as being associated with the least amount of health problems, so the best health. So if you're getting seven to seven half hours of sleep per night, that's great. But we also want to think about quality. We want to think about timing. And as we've already discussed, we want to think about regularity because those are also really important aspects of sleep health, not just how much sleep you're getting. When you say regularity, can you make this super practical for us? What would a regularity look like? Going to bed at 10 o'clock on one night when I am the next 9 p.m. 11 a.m. I like, well, 11 a.m. would be really. So jumping around the clock in terms of what time you're going to bed, also trying to keep how long your in bed is trying to sleep as similar as possible. So like four hours, one night, eight hours, the next six, that's also irregular sleep. The timing and the duration, of course, will be related to each other. So trying to go to bed around the same time every night, be in bed for at least seven hours and getting up around the same time every night as much as possible. Again, this is an aspiration. And this would be the goal for keeping your sleep as regular as possible. Has there been any experimental evidence? So evidence outside of the observational data that we have that books add manipulating sleep timing or regularity? And then saying, changes in important risk factors. - In that statement, we referenced a paper that was longitudinal in design. I can't remember if it was experimental, to be honest, but the individuals who sleep became more regular had, I think, more weight loss or less weight gain, I'm trying to remember that. So better health outcomes than the individuals who sleep either persisted as irregular or became irregular. So there's some evidence that is longitudinal design, like looking at change over time and individuals who become more regular who are end up with better outcomes. - And so when we're sleeping about sleep health in this context, in this kind of multi-dimensional application, what is the goal? So when you're getting the right sleep duration, the right timing and regularity, what's the difference in terms of what's occurring in that person's biology during sleep, during rest, versus the person who has irregularity, who is sleeping for maybe only five or six hours? What's actually different in terms of what's happening overnight and then how that affects that person in terms of what their health looks like? - That's a good question. I actually want to take a step back and say what quote unquote normal sleep is supposed to look like. So sleep can be divided into different stages. I'm sure we've all heard of REM sleep, which is rapid eye movement sleep, but there's also non-REM or non-rappid eye movement sleep, which is further divided into stages one, two, and three, with stage three being the deepest stage of sleep. And we cycle through these throughout the night. So let's say eight hours is optimal. We start out awake and we go through stages one, two, and three, maybe some REM, and then there's an awakening usually, and then we go back through this cycle and we cycle through this across the night. In an ideal situation, you have enough of this deep stage three, you have REM, and you don't have as many awakenings. But I do want to point out for particularly for your listeners that waking up is a normal part of the sleep cycle. I want to dispel the idea that healthy sleep is falling asleep and staying sound asleep for eight hours straight and then popping out of it all happy and healthy. In fact, waking up is a natural part of the sleep cycle. And so if you wake up, it doesn't necessarily mean you have a sleep disorder. So if you get anxious about waking up, now you could actually become a self-fulfilling prophecy. So if normal sleep is, are these cycles with more deep non-REM sleep in the first half of the night, more REM sleep in the second half of the night, and sufficient amounts of all these stages with limited wakings? When you sleep at the wrong time of day, so this is timing, your sleep cycles in amount of these sleep stages may be affected and it may not be as restorative. That whatever processes require sleep, such as we think brain maintenance, there's links between sleep and dementia, for example, or heart health, the blood pressure dipping I mentioned earlier. If you're not sleeping as well as optimal, then the body is not able to perform these functions as efficiently because you're not sleeping. And timing matters because of the circadian clock. Duration matters because you're cutting off a lot of REM sleep if you wake up too early. Quality matters. So like if you're sleeping somewhere with a lot of loud noises, it's going to wake you up more. Every time you wake up, there's a little cortisol pulse and cortisol makes it hard to go back to sleep if it's a long awakening especially. So quality, duration, and timing and regularity because the clock gets confused about what time it is, all impact what that sleep structure looks like and that sleep structure has important roles to play in the function of the rest of the body. What happens when you have to get up super early? So let's say you're catching an early flight and so you end up maybe sleeping in an hour or two less than you normally would. And this is a kind of multi-pronged question because it brings into the idea of wearables. I see on my whoop and that's another question as to how accurate that is. I see on those mornings that I do get a lot less REM sleep, which lines up with what you're saying because that's the second half of the sleep. And I've wondered what is the consequence of that type of sleep where your first half of the night is good, you get that deep sleep. Second half is kind of cut short because you have to get up early and you don't get the REM sleep. What is REM sleep particularly kind of good for what's happening during REM sleep and what would the consequences of doing that regularly be? - We are still trying to understand the role of REM sleep. So when you are your brain activity, if you measure your brain activity when you're awake, your brain is very active. When you're in REM sleep, it is as active as when you are awake. When you're in REM sleep, it's not, it slows down. So we think that during REM sleep, there is some function related to the brain to memory, to learning perhaps that occurs during REM sleep specifically. In fact, in infants, they have a lot more REM sleep and we think that has to do with brain development. A single night or two of losing REM is not likely to have long-term effects because we have seen in experimental studies when you restrict to somebody to four hours in bed, they still get all the deep end stage three they need 'cause that doesn't change, but they lose a lot of REM. But then when you put them in bed for now eight hours or 10 hours, there's this huge rebound in REM. So it gets made up, if it's only a few nights long. If you're doing this day after day, month after month, year after year, there could be long-term consequences. For many people, when you are a short sleeper, you're losing a lot more REM than you are the non-REM. So it's likely that some of the effects we see associated with short sleep are due to the loss of REM sleep, but that is something we're still trying to understand the mechanisms and why, what is REM sleep doing? - And do you have a view on wearables that a lot of us are wearing and whether they're helpful or accurate in terms of measuring these specific stages of sleep? - Well, I think wearables have a helpful function in making people more aware of their sleep. It's hard to prioritize your sleep if you're not paying any attention to it. I do know there are some individuals that might take it a step too far and get worried if they're sleep score or whatever your device calls it is low. So I wouldn't want someone to develop a sleep disorder because their wearable tells them they have one. And there is a name for it now. I can't remember what's called, but like people in sleep links are starting to see more people come in because their tracker has told them they have a sleep disorder. But like I said, it's good to monitor your sleep to get a sense of your patterns, your behaviors, your timing, and see where might I be able to improve and what benefit might I get from regularizing sleep? And these devices from what I understand from people who tested it are pretty good at detecting sleep versus wake. They aren't so great at detecting N3 versus REM sleep, but I think the technology will get better and better with time because to do true polyseminography and get non-RAM versus REM, you need all these electrodes, you need EEG, you need to measure the eye movement, and a wrist-worn device or a ring, they don't have access to those signals. So they're trying to use proxies. And I think they're getting better, but the biggest benefit to me is making people think about their sleep and their sleep health, 'cause that gives them the information they need to try to do what they can to improve their sleep health if it's needed. - You mentioned that waking up overnight is actually normal and not necessarily indicative of having a sleep problem. Do you think that a lot of people who wake up and remember being awake all night, are they just hyper aware of the kind of, the time where they're awake and unaware of how much they're in fact sleeping? - It could well be that there is individuals or cases with paradoxical insomnia where they think they're awake all night and if they're under wearing all these devices, the devices, well, no, actually you were sleeping. I think the quality of their sleep is probably different and there's clearly in some individuals, what we call hyper arousal, where they're just more easily woken up and active and it's hard for their brain to slow down and shut down and that can cause insomnia. I know like individuals will see them wake up at the level of their brain, but a lot of times they don't even remember it, especially when we're younger. As we get older for some reason we're more aware maybe because the arousal lasts a little bit longer and gives us time to realize we're awake. And so I think there's some difference in how much any individual even realizes that they've woken up before they fall in back to sleep 'cause there's a little bit of amnesia. Even if you were awake and you kind of open your eyes, you might not even remember it the next day. What do you think the biggest contributing fact is for having difficulty falling asleep in the first place? - There are a lot of factors that can contribute to that. I certainly stress, remination, thinking through things that are stressing you out. I catch myself doing it and I have to tell myself to stop if I'm thinking, oh gosh, I have to do a podcast tomorrow or I have a grant do and I have to stop thinking that and redirect my internal dialogue to something more relaxing. I think people who are really busy lives running and running and then they're like, okay, now I need to go to sleep and they don't give themselves enough time to wind down and they expect to fall asleep quickly. They will fall asleep quickly if they're very sleep deprived but if they're not extremely sleep deprived, they will have a little bit of trouble 'cause you do need to have that wind down period. We talked about light, noise, sleeping and a noisy environment. Caffeine, I've had people tell me, oh, I have so much trouble sleeping and I can't sleep and I'll say, well, do you drink caffeine in the afternoon or evening or coffee and they're, oh yeah, but it doesn't bother me. But you just told me, you can fall asleep. So caffeine can impair sleep. It can last in the system for many, many hours. So if you're having trouble falling asleep, avoid caffeine and purchasing the afternoon, those are some of the environmental, like I talked about, noise but temperature, if it's too hot or too cold, these can make it difficult to fall asleep. Anything that leads to discomfort and anything that makes you feel, not rested, not calm. 'Cause if we wanna have this period to wind down and prepare ourselves for sleep, and if we don't allow ourselves that or there's something interfering with that, that'll make it more difficult to fall asleep. - Yeah, I know that I'm the same as you if I'm going to sleep with this huge list of things running through my mind that I need to do, attend to, then falling sleeps very hard. And I remember a friend told me this kind of visualization practice, and I do do this sometimes where I think about all those things, say to myself, now's the time for rest and deep sleep, those things are gonna be there in the morning. And I like to imagine just that list of things, like you know, book and putting it up on a bookshelf. And I just kind of, I just try and all the really let go of it. And it seems to help. So maybe people can try that out. What about waking up and not being able to get back to sleep? I think a lot of folks maybe wake up because of the natural cycle, what you were talking about, and/or need to go to the bathroom. And then it's 4am and all of a sudden, any problem that you have in your life is absolutely intensified. It's a thousand times worse, and it's difficult to fall back to sleep. So do you have any kind of advice for that person who's falling asleep fine, but 4am waking up, can't get back to sleep? - Yeah, that's a common one, especially as we get older. For whatever reason, like as we get older, we all know we can't sleep until noon anymore, and the ability to fall back asleep quickly even after being woken up gets more difficult, especially the 4am or the 5am is because we've already slept enough that we've gotten enough sleep that we're not super sleepy anymore. And so I think, similar to falling asleep, if you've gotten up and now you're trying to get back to sleep and you can't, you have to still avoid rumination, avoid thinking about that list, and come up with these cognitive practices to rest our mind and body, and to allow us to go back to sleep. I think one of the, in my opinion, one challenge is if we start worrying about the fact that it's 4am, and oh my gosh, you have to get up in two hours or three hours, that is gonna make it even harder to fall asleep. And so working on these cognitive practices to try to avoid anxiety related to having woken up will help allow us to fall back to sleep, because anxiety and sleep do not go well together. So we need to minimize anxiety and become as relaxed and restful as possible to allow us to go to sleep and cut ourselves some slack. Okay, I'm up for a few minutes at 5am. I'm not gonna think about work. I'll just sit here and meditate or whatever works for me and be okay with not falling asleep in a minute or two. - What do you think about getting out of bed to go to the bathroom? I've recently heard, and then I think this is a little bit controversy, all I heard a guest on another show who said, "You absolutely should never get out of bed unless it's an emergency to pee and you should just hold on." And that if you get out of bed, your heart rate's gonna go up above 60 and you won't be able to fall back to sleep. - I think that's a hard ask for some people, especially if you're on medication. Some medication like will cause the need for frequent yearnation. So I wouldn't, I think it's more about, and I think what this person was probably getting to was the increased anxiety or alertness or signaling that is associated with standing up, walking to the bathroom. By the way, I never turned my light on in the bathroom. I have a night light so that there's no big bright light like to wake me up even further. And then when you get back into bed, again, you're not gonna fall asleep in 30 seconds unless you're really sleep deprived, allow yourself that time to unwind again and fall back to sleep. But I think personally, the problem with not, if you've woken up and now you're aware that you do need to pee, you're not gonna get back to sleep anyway 'cause you're gonna be obsessing over the fact that you're not supposed to get up to pee. So I don't think that would actually ever work unless you're really tired. - Yeah, I can put my hand out, that's happened to me before. - Yeah. (laughing) - You mentioned that you don't turn the bathroom light on. If you're happy to share what other kind of sleep habits, or how would you describe your own sleep hygiene in terms of the things that you try and get right most of the time? - Yeah, well, I think I sort of self-selected to sleep research because I think I'm naturally a longer sleeper. And so, my colleagues are a little more understanding if people don't wanna get up for 6am meetings. But so I've always sort of prioritized my sleep, like I said, going to bed is regular as possible. Bedroom around 67 degrees whenever possible. As dark and quiet, no TV in my bedroom, absolutely not. I try to avoid spending too much time on my phone right before I wanna go to bed, easier than done half the time, but that's a goal. And I do avoid it. I have my dinner around six or something, I don't eat again until after 7pm. So I think I try to follow these things. I don't know that I always did all of them because I knew they were related to sleep health. I knew they made me feel better if I did it this way and I slept better. Now, life often gets in the way. The worst thing I ever did for my sleep was have a kid. We all know having young children is going to mess with your sleep and you just have to do the best you can. I've talked before as well about competing priorities. There's only 24 hours in a day. And I know many of us have other things that absolutely have to be done. Work, childcare, household stuff. We wanna have a life. So I do recognize that not always are we gonna get that 70 hours in bed. But again, just like any healthy lifestyle behavior, that is the goal and regular sleep, quiet bedroom is the goal and we do what we can to adhere to that whenever we can. And that's what I do. - I think that brings up an interesting point. I'm glad you both that out up about kids because I think sometimes when people hear about circadian biology and just human physiology in general, and we've mentioned things like increased risk of dementia, really scary, right? There's this idea that our physiology is super, super fragile, but there is some resilience built into these systems, right? - Yeah, we wouldn't be here. There wasn't some, right? Yeah. - Right, so that person who is having four or five or maybe more years of disrupted sleep because they have little kids, it would be important for that person to understand that they are also resilient. - Yeah, I mean, we are the adaptive species, right? We wouldn't still be here if we weren't. And we've overcome some of our biology, like we don't, unlike many animals, we don't go to sleep the minute we feel sleepy, maybe we should, but we don't. But we do adapt to that and we, either whether it's biological adaptation or cultural adaptation coming up with ways to mitigate some of the consequences of not getting enough sleep. But if you've had a bad month or even year of sleep, it doesn't mean you're doomed and you should give up. Just like smoking, quit smoking now, regardless of long you've been smoking, there's gonna be a health benefit. The same was sleep or circadian health or diet and exercise for that matter. Like start, anything you start now is gonna have a benefit, regardless of what you've experienced in the past. And I don't think we're doomed. I don't think like, once we've had kids, that's it, give up on sleep and circadian health. We do what we can when we can, yeah. - As a scientist, is there anything in the wellness space which I'm sure you keep an eye on? That people have kind of gotten terribly wrong about circadian health or about sleep health. Is something that you would want to correct if you had a megaphone? - One thing that's been wrong in the past is that as we get older, we need less sleep. That, oh yeah, grandma or great grandma is, only sleeping four or five hours, but that's all she needs. And I think the field agrees that we don't need less sleep as we get older, it's just that there may be other factors interfering with our ability to get good quality sleep. And so I wouldn't want someone to just dismiss an older person with poor sleep or insufficient short sleep as well, they're fine, it's not a big deal. Like I think we need to understand that sleep health remains important through our entire lifespan. And not just as kids or young adults. Like this is something we need to think about and prioritize our entire lifespan. - I think we've done a good job and by we, I mean the field and everyone in sleep science and circadian science at getting sleep into the mainstream idea of what is healthy lifestyle. I think when I first started many, many, many years ago, we won't count. A healthy lifestyle was all about diet and exercise. And as a field, we try to get sleep added to a healthy lifestyle that it's the three pillars of health, not just two. I think it's important to recognize that they don't operate independently. Like when you sleep poorly, your appetite might go up more than it should and you're more likely to choose unhealthy food and you're less likely to exercise. And so they're all really related to each other. And it's not a situation of choosing between them. We all three should be considered as you're trying to develop a healthy lifestyle. Lifestyle. So I think isn't always one or the other. Like sometimes you have to make choices when time is an issue, but I think we need to consider them all together and not dismiss one in favor of one of the others. - You're allowed to have your favor, though. - You're allowed to do that. - You're gonna be in your favor. And I get a question that I get a lot and I thank you for not asking me it is, well, should I exercise or should I sleep? It's like, well, and I get the time is, you know, there's finite number of hours in the day and so it is sometimes that decision. But I don't think a nutritionist has ever asked, should I have a healthy diet or should I exercise because I'm not doing both? Or maybe they are, I don't know. But I think it's trying to do as many of these healthy behaviors as possible. But again, recognizing these are goals and life gets in the way sometimes and to give yourself a break when sometimes you just can't achieve all of these goals. And I want sleep to be considered part of that healthy lifestyle. - And how do you think patient outcomes could change if more physicians or clinicians in general were talking to their patients, not only about sleep duration, but also about timing and regularity in some of these other dimensions of sleep as you guys outline in the scientific statement. I think if the physician is asking, I think that's a signal to the patient that these things matter. I mean, many patients or people general public will hear in the news or podcasts like this that it's important. And for those who don't, if their doctor is asking them about it, it's a recognition that this is important. And that's a great first step to getting people to appreciate these other aspects of sleep health that are important for their health. Eventually, we hope to have not just doctors asking the questions, but be able to have ways for the doctors to then advise their patients on, okay, well, this is what we should do to maximize your sleep health or your circadian health on all these different dimensions. But even just getting awareness increased, I think, is really important for getting to the point where we really leverage sleep, circadian health for overall health. And are there any significant research gaps that you feel are kind of most urgent right now in this space? Well, what I would like to see more research on is something I alluded to earlier, which is what can we do to improve sleep health, circadian health in the general public? We have, as well as specific patient populations, we're like we talked about light treatment. How do we best advise people to get supposed to light when we know chronotype matters and most people can't just tap into their internal clock to see what time it is? How do we decide when the best time for different therapies are or exercise or meals? I think figuring out what are some of these behavioral interventions that can help support or increase circadian health as well as sleep health. I think we need to move that field more to really give people a toolbox to choose from that they can use to improve their own health. It seems like at the individual level, we need a better way of assessing chronotype. And then even then, once you assess it, if you are a night owl truly and fabricating it, then you need it to be socially accepted. I think for some night owls that are able to, they self-select for jobs that are later in the day, but not everyone can. I don't think it's that being a night owl in and of itself is a health risk. I think it's a night owl who is having to live a social schedule that's more like a morning person or intermediate person and is causing the circadian disruption that we've already talked about. And that's what's leading to a lot of the health problems associated with being a night owl. So the truly morning lock who takes on job as a nightclub promoter. There is some, like morning types who end up being night shift workers do worse. The night owls who end up being night shift workers. So the more we can align our work shifts with our internal clock, not only will the person be healthier, but their work quality and productivity may increase. So this is a benefit to employers as well to try to align those as much as possible. There's not always options, but if there is, it's something to consider. Chris, and this has been fabulous. Thank you so much for all of your work. Is there anything that we missed today or anything you wanted to add to or just leave people with? I mean, again, both sleep and circadian health are part of a healthy lifestyle. And we talked about a lot of different aspects to sleep out to circadian health and things to think about. I want, like you said earlier, to everyone to feel overwhelmed like this too much, but to just take it piece by piece and think about which one thing might be something you can try to improve first. These are goals. This is what an optimal lifestyle would look like, but we don't expect everybody to suddenly be able to follow every single piece of advice, but to really build on it and work with what works best for them over time. I don't want to overwhelm people and cause insomnia. Thank you very much for being with us today. We appreciate your time. Thank you. I'm a spun. There you have it, friends. I hope you enjoyed this episode. If you did and want to stay up to date with future episodes, be sure to hit that subscribe button on YouTube and follow on Apple or Spotify. Finally, thank you for showing up and the effort that you're making to take control of your health. I look forward to hanging out with you again in the next episode.