0:00 Hi everyone. I'm Jen Flynn, Senior Director of Global outreach at the Harvard Kenneth C. Griffin Graduate School of Arts and Sciences. And on behalf of Harvard Griffin GSAS, I want to thank you for taking time out of your day to join us as we learn from our distinguished alumna, Elizabeth Klerman, M.D., PhD '90, about why sleep matters more than you think. Before I jump to our first question, I'd like to introduce our esteemed guest, Doctor Elizabeth Klerman, M.D., PhD '90, is a Professor of Neurology at Massachusetts General Brigham Hospital and a Scholar in Medicine Fellow, Hinton Society at Harvard Medical School. At Massachusetts General Brigham and Harvard Medical School, Dr. Klerman's efforts are concentrated in clinical and biomathematical research, teaching, and clinical practice.
0:45 Her areas of research are the application of circadian and sleep research principles to normal and pathophysiologic states, and mathematical analysis and modeling of human circadian sleep and neurobehavioral mood and performance rhythms. In 2024, she was awarded the Sleep Research Society Distinguished Scientist Award. Dr. Klerman also mentors students and junior faculty locally and internationally about conducting and analyzing patient-oriented research, and we are so thrilled to have her with us today. Thank you very much for inviting me to participate. Yeah, we're really so delighted to have you. And we have huge interest amongst our alumni for this topic, so let's jump in and start broadly. So what is the primary purpose of sleep, besides rest?
1:31 What does sleep allow our body to do in terms of healing, detoxification, memory consolidation, immune system functions, metabolism, what else? We'd love to start with this first broad question. So it's an excellent question. And we don't know the answer. All of the things that you said are correct. Sleep enables the body to, you could say, body prepared to be awake. And that means that it handles-- it allows all these functions to happen better because some sort of recovery or something else happens when people are asleep. And we know this from studies in which people get insufficient sleep. And that case is the metabolism changes, mood changes, other physiologic things change. So we know from them that sleep serves
2:18 an absolutely vital function. As a matter of fact, one of the founders of the field said that if sleep doesn't serve an absolutely vital function, then it's the worst mistake that evolution has ever made. If you think about it, during sleep, you don't do the things that most people associate with evolution, which is procreation, defense, and eating. None of those are happening during sleep. And yet every animal sleeps or has a sleep-like behavior. And so there must be something happening that is evolutionarily advantageous so that the body defends the need for sleep. And one of these things you could say is the most basic thing, is that for at least for humans, we don't operate very well at night. And so if you start off by immobilizing us by sleep so
3:05 that we don't wander around in the night where we are easy prey, all these other things can happen because we're now immobile. We can now do recovery of all these other functions. And so it may be that all these things co-evolved. That's a hypothesis. It's no way of proving it. But my feeling, my feeling, my personal feeling is that these things co-evolved. Once humans and other daytime active creatures were no longer active at night, or nighttime active creatures were no longer active during the day, this was a chance for other physiology to consolidate. So you talked about the different things that happen during the night that we don't do during the day,
3:52 and how sleep helps there. But is there an optimal amount of sleep? This question came in from hundreds of people, I would say. Is there an optimal amount of sleep for minimizing health risks or optimal kind of performance, and how does that change as we age? So it's a great question. And the answer is we don't know if it's the same amount of sleep is optimal for every single one of those functions. So it may be-- and I'm making this up-- that for metabolism, you need six hours of sleep, but immune function, you need seven hours of sleep. So the amount of sleep that you're going to get is a compromise between two factors. One is called the circadian factor, which is at certain times of day, your internal circadian clock promotes wake, then at other times of the day it promotes sleep.
4:37 And so even if you've been awake all night, the circadian system says it's time to wake up. And the second thing that governs how long you're going to sleep is the homeostatic factor, which is how long you've been awake. How much of a drive have you built up, because you've been active over-- you've been awake, or something else like that has happened. And there's an interplay between the two of those that governs how long you're asleep. So the main factor that affects how much sleep most people get is how much time they allow themselves to sleep. So for most people-- not everybody, there are people with sleep disorders and circadian rhythm disorders. I tell them, can you wake up without an alarm clock or a child or a dog? If you're waking up with an alarm clock,
5:22 you are by definition, not getting enough sleep, because the alarm clock is waking you up. We usually tell people it should take you a few minutes to fall asleep. You shouldn't fall asleep the minute your head hits the pillow. And then so we tell people, how much sleep do you get on weekends or vacations? How much sleep do you get then. It's probably a little more than you need because you're making up for lost sleep during the day. The amount of sleep an individual person needs depends on the individual person. So some people, there are probably people who only need five hours of sleep, but there are probably many fewer people that need five hours of sleep than think they need five hours of sleep. The average is probably around eight-ish hours. How much sleep you need varies across your age group. Absolutely children, babies and children need much, much more.
6:11 Adolescents still need more. The recommendation is 9 to 10 hours. As adults 22 and older, we still recommend approximately eight hours of sleep. And it may decrease over time, but it's hard to know. I would still say still aim for how much sleep you need, where you wouldn't need an alarm clock to wake up. Now, that's a goal. I know that people have jobs and children or older parents or all these other things that interfere with their ability to get the amount of sleep that they need. That is a societal problem. It's a personal problem. It's all these other things. You just asked me, how much sleep do people need? And I'm saying, if you can sleep without somebody waking you
6:57 up, that is a way to figure out how much sleep you need. I realize not everybody can do that, but it would be good if they could. Yes, we'll get to a little bit of that in just a second, but I want to just probe on this just a second longer, because I've heard you give a comparison between an alarm clock and a washing machine. And that really helped crystallize for me about really helped me think about sleep in a different way. Can you share that with us? Sure. So that actually comes from Doctor Till Roenneberg in Munich, Germany, where he says, if you're using a washing machine, would you ever stop it mid-cycle? Why would you stop it mid-cycle, say, oh, no, I think it's done? The machine is developed to clean the system and do all these other things. So the same thing for sleep. Sleep is designed to do a whole number of functions.
7:43 Why would you stop it early? So is that what you remember my saying? - Yes. Yeah. And I really had not thought of sleep in that way, that cleansing factor that happens. So that was an important analogy for me. Going back to the different phases of sleep, when you said, there's an optimal-- there may or may not be an optimal amount of sleep monolithically, but maybe for individuals, but does sleep phase matter? And what happens in each phase, the REM, deep, core? How much do we need? Is there an optimal amount of each phase to fully restore ourselves and maintain good physical and mental health?
8:29 So I think you mean sleep stages, just a slight correction. Sleep is composed of two major sleep stages. One is called rapid eye movement sleep, during which most dreams occur, and one is composed of non-rapid eye movement sleep, when it's not rapid eye movement sleep. And then stages-- non-rem sleep has stages 1, 2, and 3, which sort of correspond to the depths of sleep. Different things happen in different amounts of-- the different stages of sleep. I know of no way of saying, oh, I'm only going to do REM sleep, or I'm only going to do non-REM stage sleep 2. So saying how much is optimal, since you can't do anything about it, I don't necessarily know what to say. There are some drugs that suppress one of these or another, and that's
9:14 up to a physician to decide and their patient to decide whether or not the drug is worth the changes that it's going to do in sleep. So you also need both of them. So you can't just have non-REM sleep or you can't just have REM sleep. They cycle across the night. And so you also can't preferentially choose one versus the other. But if you're waking in the night several times, that was definitely something that-- a common theme that came through in [INAUDIBLE] received in advance. You may be getting more of one stage than another inadvertently because of that. And are there impacts there that we can mitigate against? So I don't know of any data that suggests
9:59 if you're waking the middle of the night, it means that you're preferentially getting more of one stage of sleep. They may exist, but I don't know about it. Older people have more problems staying asleep, yes, but their ability to fall back asleep is the same. It's just they're waking up so many more times, there will be more times when they're awake for a long period of time. You mentioned about the staying-- we're supposed to be asleep in the night, but how does being a night owl versus an early bird affect sleep? And I think sometimes the times when you can sleep, you can't often control that. And we'll get into that in more depth in a second. But we have these concepts of early riser and late to bed, maybe late to rise and early to rise and early to bed.
10:46 How do those affect sleep and health? So they definitely affect sleep because as you said, some people are early risers and some people are late risers. We know that also changes across time, across ages. So younger people tend to be early. And then as they go through adolescence, they get later, later, and later. And then as they-- around 22 or 23, they start becoming earlier. So you think all those adolescents who can't go to sleep before midnight or 1:00 AM, that's their biology. It's not that they're trying to avoid their parents, anyway. And then we get earlier again. So that changes over time. In addition, there are more people-- there are people who are more early birds, and there are people who are more late owls. I think of it as evolutionarily advantageous because you
11:32 want some people awake in the morning to guard whatever, and you want some people awake overnight to continue guarding you. You don't want everybody awake all at the same time. If you've had kids and you have sleepovers, you want one parent to be able to stay awake through the end of the sleepover, and you want the other parent awake when everybody starts waking up. So you expand that to be a more defending your village sort of thing. The issue about how does that affect health, well, it depends on whether or not you get to sleep when you want to sleep. And during the pandemic, there were some reports that people who were very late owls and weren't getting enough sleep and were having problems with work were actually doing better because they didn't have to get up to go to work because they were working at home. So they had fewer--
12:19 they had more time to sleep in. And there was also a report out of Australia, out of the Monash group, showing during the pandemic that some teenagers got to sleep more, once again, because they were doing at home, school, at home. They didn't have to get up earlier. They're already late. So the problem happens is the conflict between people's biological tendencies to be morning versus evening and society. So if society says you have to be at school at 8 o'clock in the morning, and your body clock doesn't want you to go to sleep until midnight, and you have to get up an hour and a half beforehand to eat, shower, have breakfast, or whatever, late people aren't going to get as much sleep. And so the question, part of the question is, how much of the disadvantages of being a late person are related to the fact that they're not getting sleep,
13:04 and how much of it is really the fact that they're on the wrong time zone? It's almost as if for me in Boston, a teenager is on the California time zone and trying to operate on the Boston time zone. And so both are probably involved. So yes, it does affect, make a difference in health. And part of this, actually, is called social debt. So social debt lag is people having what looks like jet lag because they have one sleep schedule during the week, especially if they're a late type, and they have another sleep schedule when they're on their free days. So imagine a teenager has to get up at 7 o'clock in the morning on school days, and then on free days if they don't have sports or something else, they now get up at noon. So they have a big shift to when they go to sleep
13:50 and when they wake up. And it looks like jet lag, except it's socially induced because there's a difference between their biological clock timing of when they want to go to sleep and what society is requiring that they go to sleep. Now, this is related to another question that I'm sure is going to come up is this is also related to what's going to happen in a couple of weeks when we enter Daylight Saving Time-- when we end Daylight Saving Time and start Standard Time. That's right. You're currently in Daylight Saving Time. That's right. Daylight Saving Time, our clocks, which are our body clocks, which know the time of day from lighting, not from the clock on your wrist, during the summer, during Daylight Saving Time, they are off by an hour because that's the definition of Daylight Saving Time. We're about to switch to Standard Time, when the two are aligned. And I am part of a group of people
14:35 who are saying there are many adverse physiologic effects of both the shift and what happens when you're on Daylight Saving Time for a long time on health and safety. And the really cool way of looking at that is both people who have social jet lag and looking at that, but also looking, at least in the United States, you can look at time zones, and not all the time zones match where they should be. So the time zone should technically match longitude from Greenwich mean Time. But because of where states' borders are, some of them overhang, and so it's more than an hour from East to West within a particular time zone.
15:21 And on the Western part of the time zone, which is the equivalent of more social jet lag, there's more diabetes, there's more accidents, there's more adverse health effects. And so that is an analogy of daylight savings time. It's analogy of social jet lag. And it's an analogy about what happens when your body clock is not aligned with this social time that you're trying to have it be, which sometimes happens with late owls. Did I tie all that together, or did I confuse you? Oh, no, that was great. I just want to probe a little bit more on the Daylight Standard, Daylight Savings Time, because I know there have been votes over the years, including one as recently as March of this year, to make Daylight Saving Time permanent year round. So you shared a little bit about how that would impact body clocks and health,
16:08 but what would the impacts be if this were to be adopted? Do you think we would see more adverse health outcomes as a result of this? So there would be expected to be more adverse health outcomes. I'd like to point out that the United States had permanent Daylight Saving Time twice already, and it ended because of unpopularity. There was one in the early 1900s, and there was one around the time of the gasoline crisis. It had also been tried once in Russia, and it ended because of unpopularity. So it has been tried before in the United States, and it's ended because it was unpopular. There are the effects on health that I've already mentioned. You get less sleep at night, and therefore all the adverse effects of less sleep at night.
16:56 It's the equivalent of living in Chicago and trying to work on Boston time. Just you're staying up too late. You're having to get away too early in the morning. There's evidence of increased traffic accidents that is also there. And also in terms of kids going to school, if you live in Seattle, kids will go to school in the dark for months at a time. During a previous time, there were more cars-- as might be expected, there more accidents. If kids are out in the morning, in the dark, trying to go to school, more accidents for kids. And the other thing to mention is people who get up earlier, not just children, but there are also people who have to be at work really early in the morning, so that person that's giving you your 4:00 AM coffee or is a TSA
17:41 person. And they tend to be of lower socioeconomic status. Yes, there are people of high socioeconomic status who choose to get up at 4 o'clock in the morning and jog, but more people who have to get up at 3:00 or 4 o'clock in the morning are of lower socioeconomic status. And if they're now going to be in the darkness even more because of permanent Daylight Saving Time, they're going to get even less sleep, and it's expected that their health will be even worse. Yeah, so essentially what you're saying that there is perhaps a socioeconomic factor for some in terms of sleep, and that falls disproportionately on certain communities than others. Because they tend to be the people who wake up earlier. And that means they're going to be even more disproportionately affected. Because when people say there's more light in the evening,
18:31 there's the same amount of light across the day. It's just shifted later in the evening. You stay awake later, but the alarm clock still goes off at 4 o'clock in the morning. And so you've now been awake later because it looks light later, but the clock is later. So once again, just think if you're in Chicago time. It looks like the light is on later. It's light later at night, but you're waking up by New York or Boston time, and so you're getting less sleep. And you're also trying to do things at the time of day that is not appropriate for you. And so that's going to affect health and safety and other physiology. So let's probe into that just a little bit more. So what are the cognitive, physical, emotional, maybe even economic effects of sleep deprivation? What are the impacts on decision making or memory, relationships,
19:18 productivity? Could you share a little bit about that from your research? So there was an interesting set of studies out of the University of Chicago, where they put people on six hours of sleep, and within a week, people's metabolism looked like prediabetes And we know that there are more and more people in the United States who are overweight and who have prediabetes or diabetes. And so one question is whether if they got more sleep, would they not have some of these conditions? We also know that eating late at night, which happens when you're awake for a long period of time, is not metabolically as good as eating during the day. So calories are not necessarily calories across the day.
20:06 There's an old saying that you should eat like a king in the morning, like a prince in the afternoon, and like a pauper in the evening, and you certainly shouldn't eat within a couple hours of bedtime. And I kept on saying that, keep on saying there should be an exception for ice cream, but I've been told there is no exception for ice cream. For immune function, whoever was right, if you don't sleep enough, you're more likely to get sick. You're less likely to have all the positive effects of a vaccine if you've just been vaccinated. For mood, well, just think of a three-year-old who hasn't gotten enough sleep. For safety, car accidents, if there's a single vehicle car
20:51 accident in the middle of the night, somebody fell asleep at the wheel. It's rarely something else that when the body decides it wants to go to sleep, it goes to sleep. And you don't know you're asleep until you wake up. So the article, the Colloquia article started with my falling asleep at the wheel. I wasn't aware I was asleep. I was aware I was tired, but I wasn't aware I was asleep and luckily somebody was sitting next to me who said, Beth, what's happening, and woke me up and I stopped driving. There's also more errors and accidents. So Exxon Valdez and other major accidents are associated with people having insufficient sleep. There's more medical errors. Decision making, people more likely to perseverate,
21:39 so they're more likely to keep this particular and not necessarily notice that there's an alternative. They can keep the car on the road, but they might not notice that the car is running out of gas. So you're able to focus on one thing, but you can't necessarily shift your decision making. Let's see. We know that insufficient sleep is associated with changes in some psychiatric disorders. And when I went to medical school, you were taught that, for example, some types of depression were associated with insomnia. But it's been more recently found out that if you treat the insomnia, the incidence of depression might go down. So it's a two-way. It's not just depression causes insomnia. The sleep disturbance may in turn affect the depression. And certainly, insufficient sleep,
22:26 if somebody was awake all night, they may be more likely to go into have a manic episode or some other psychiatric illness. So psychiatric illnesses. Cardiovascular. I haven't even talked about sleep disorders associated-- other sleep disorders. Yeah, there's a lot. But we did a study in which we took healthy people and we put them on insufficient sleep, and also the equivalent of shift work. And their blood pressure went up, even though they were healthy. And Andrew McGill, who was a post-doc of mine, is at Oregon Health Sciences University, did a study where he took new bus drivers and they were all healthy when they started. They got randomized by somebody else, not him, to either working the night shift or the day shift, and the people working the night shift who also got less sleep, their blood pressure went up compared to the people who didn't. So-- do you want me to continue going through organ systems,
23:13 or have I convinced you that-- Well, I think that you're touching on a number of questions that I had hoped to ask. So I'll just maybe follow along, because you mentioned sleep disorders. What are the long term impacts of sleep disorders like sleep apnea, restless legs syndrome, REM behavior disorder, sleepwalking? How do those impact our long term health? So each of those has different outcomes. So the issue about sleep apnea, which is when people stop breathing during sleep, if it's obstructive sleep apnea, then just think of what happens. People tend to wake up in order to have to start breathing. And so when you fall asleep, if you think about it, your muscle tone relaxes. This is one of the causes of sleep apnea, not the only one, but it's just one way. And for some people, their breathing tube relaxes
24:02 and you'll hear a loud snore, and then they stop breathing. And then you'll hear a loud snort when they wake up and their tube opens and they can-- their breathing tube opens and they can stop breathing again. So the obstructive sleep apnea is associated with mostly cardiovascular problems and other cognition problems, because people are not getting enough sleep and they're having these huge bursts in blood pressures. They wake up sort of startled. That's one of the many things that's issue with obstructive sleep apnea. If you can't share a bed with your bed partner because they snore too much or too loudly, or you hear them stop breathing, then they really should go see somebody about getting treated. It is treatable by many things, and it should vastly improve
24:50 your health in many ways. Restless legs syndrome is something which people kick during sleep, and it may be caused by certain abnormalities in your bloodstream, and so you should get that checked out and see if those can get fixed. REM behavior disorder. When people wake up and act out their dreams, it's very interesting. People with REM behavior disorder are much more likely to have certain neurologic diseases in a few years. There are some active studies going on studying this. It's not known why. So if you know somebody who really violently acts out their dreams, I would suggest that once again you go see a neurologist, tell them that this is happening and see if you can be involved in figuring out why this happens, or at least get monitored
25:35 as the disease progresses. And once again, not everybody, but a high percentage. Sleepwalking. If the environment is safe, people usually outgrow sleepwalking. It's usually mostly something that happens in children and adolescents. Obviously, there are adults. I remember seeing a movie about an adult, and you have to make sure the environment is safe for them. I guess I want to emphasize that sleep medicine is a field with diagnoses and treatments, and just like cardiology and other illnesses. And if you-- we haven't even mentioned one of the most common ones, which is insomnia, or some of the other ones like circadian rhythm sleep-wake disorders, like people who have to work shift work, or jet lag. There's also other circadian rhythm sleep-wake disorders
26:22 associated with profound Alzheimer's disease, where people lose their 24-hour rhythms, or blind people who have non-24-hour rhythms because they can't-- because since they're blind, they can't synchronize their circadian clock. So sleep disorders is a real field these days. It has been for around 25 to 40 years, or whatever. And we wish that more people would take advantage and think about it. If you're tired, we usually say if you're tired after being in bed for eight hours, or if your bed partner complains about your kicking or snoring or snorting or just being too unpleasant, you may have a sleep disorder, and we'd like to suggest that you go see somebody about it, because maybe we can help. So you mentioned insomnia, and that absolutely
27:08 came up in some of the questions that we received in advance of this. So there are times when you want to sleep, but you just can't because you have insomnia. Can you share a bit about that from the circadian perspective and what's happening that doesn't allow us to sleep? And is there a way that we can sync our body clock with the outside environment in some way, too? So the best way of syncing your body clock is having light, especially in the morning, which is another thing that gets disrupted when we're on Daylight Saving Time, but anyway. So the best way to align your clock is by having light, especially in the morning, period. There are many causes of insomnia, but first, I actually want to go back to something that we came before that's going to come up with insomnia, which is while your average amount of sleep might be eight hours,
27:57 you can still have variability in the amount of sleep that you have. So I did a study in which we put people in the lab and they got 16 hours of sleep opportunity per night, 12 hours at night and four hours during the day. And after a couple days on this, the younger people averaged out at a little over eight hours of sleep, which means you have to be in bed for more than eight hours in order to get eight hours of sleep. And the older people averaged a little less than eight hours, which means they have to be in bed for eight hours in order to get a little less than that. But what was really interesting was that once they'd reached this overall baseline steady state, there was huge variability. So some nights they would get eight hours, but other nights they only get five. And then the next night, they might get six,
28:42 or back to eight or nine again. So I usually tell mostly my friends, but others that if one night you don't sleep well, don't worry about it. Give yourself-- don't lie awake worrying about why you're not getting enough sleep. Occasionally, one or two nights where you don't get as much sleep, if you're giving yourself enough opportunity to sleep, I don't usually worry about it. Now, let's get back to insomnia because not getting as much sleep you want is insomnia. So if you are frequently not getting enough sleep, there's different kinds of insomnia. There's the kind where you can't fall asleep. There's the kind where you fall asleep and you can't stay asleep, and then there's the kind where you fall asleep but you wake up too early and you can't go back to sleep. In terms of the biological clock, the first and the third one are the ones
29:27 where we think about may, not necessarily, but may have circadian influences. So if you're a late type, if you're an adolescent and I put you in bed at 10 o'clock, you're going to have sleep onset insomnia. You're not going to be able to fall asleep. And it may be that you have to go to bed at 10:00. You want to try and go to bed at 10:00, because you have to wake up at 6:00 to go to work, and you don't want to go to bed at midnight because that when your body clock wants you to go to bed at midnight, because you want to get eight hours of sleep, which I hope you want to get. So that's-- and the other end is suppose you are an early type, and your body really wants to go to bed at 9 o'clock at night, but your partner is a late type, or you want to stay up and watch movies, or you want to have an active social life, and therefore you don't go to sleep until 11 o'clock at night, but your body clock, remember, I said your body clock influences
30:14 when you go to sleep and when you wake up, wants you to wake up at 5 o'clock in the morning. So some causes of insomnia are because there's a mismatch between the internal time and societal demands. Other causes of insomnia are not. And if you go to a sleep clinic, hopefully they can walk you through what is the potential cause of insomnia and what can we do to help you sleep better. Of note, especially in older people, the recommendation is that people not take medications for long periods of time or chronically for insomnia. It is far better to do cognitive behavioral therapy for insomnia and other methods than taking a pill every night for a long period of time. You can take a pill when something
31:00 has happened for a short period of time, something stressful has happened in your life. But the recommendation, especially for older people, is that you not take a pill every night. And it may get worse for a couple days or a while, if you've been on pills for a long period of time. But overall, the recommendation is that you not take medication for insomnia. So I suggest if you have insomnia, please see a sleep physician or a sleep psychologist. And there are sleep psychologists who do terrific work, not just sleep physicians. And so see somebody. See if you can figure out what is the cause of the insomnia, whether it's circadian or other behavior, and then we can possibly, hopefully, tailor the treatment. Insomnia is a big catch all, and we want to make sure that we give the right treatment
31:45 for the right cause. Does that make sense? Yes yeah. There are two kind of questions. One is more short term, one is more of long term, I guess, that I want to ask. So I'll ask them both and I'll let you answer them how you will. So as you mentioned, there are some times when we can't get enough sleep due to outside factors. You mentioned this earlier in our conversation. You could have small children who wake you up in the night, or you might work shift work, or you might be a pilot, or a first responder, or a medical trainee who's working overnight all the time. Or you might be in menopause, or you might be caring for someone with a health challenge, or have one yourself. You might live in a noisy neighborhood or where there's a lot of light pollution. When there are these outside factors that are influencing our sleep and also maybe creating health challenges as a result. Is there anything
32:31 that we can do in the short term, and maybe in the longer term? And then for long term sleep deprivation and chronic conditions that result, can the effects of sleep deprivation be repaired or reversed in some way? Can you sleep your-- I'm going to start with the second one. We don't know the answer to that. I don't know how to do that. There's no sort of-- you're not going to do a randomized controlled trial of that, which is the gold standard for most studies. And so we don't know if you can reverse the long term effects of insufficient sleep. There's the worrisome papers that have come out that suggest insufficient sleep in your 50s may increase your risk of dementia, but by the time you have dementia,
33:19 you probably can't go back. Sleeping more probably won't reverse the dementia, though that'd be a really interesting study to see. So some of it is we just don't know the answer to the second question about whether or not you can reverse it. However, I would say try. Just in terms of long term, but certainly in terms of short term, if you start sleeping more, some of the effects may reverse in terms of metabolism or safety or cardiovascular outcomes. Certainly, if you sleep better, we would expect on a short term some of these things might improve. And then in the long term, hopefully they would also affect. So don't try. Don't give up. I mean, do try. Don't go up-- don't give up. Ugh. Do try. Don't give up. What was the first part of the question again? Oh. No, there are so many things that are outside of our control.
34:04 Yeah, what can you do? Right. So I would say control what you can control and work with advocacy groups or your environment or your politicians to control what you can control. So if you can, give yourself enough time to sleep. Don't watch horror movies just before you go to bed. Try not to have caffeine. It depends on how susceptible you are to caffeine. Don't have caffeine in such a way that it will affect your ability to fall asleep. Alcohol tends to help people fall asleep but then disrupts their sleep. So along with don't have a horror movie because Halloween's coming up, don't have a stressful conversation or pay bills just before you go to sleep. I mean, if you have kids, the way I put my kids to bed was you read them nighttime-- they got a bath, you read them a nighttime story, you sat with them quietly,
34:50 and then you put them to bed. There was a chance for the body to know that we're going to go to sleep, and this is what we're going to do, and eventually their body's going to say, oh, I'm going to go to sleep. They didn't like-- you don't have a kid go charge-- I didn't have my kids. Obviously, other people can raise their kids other ways, sort of charge and then put them in bed and say, go to sleep. And so giving your body a chance to say, oh, I'm getting ready to go to sleep may indeed help you go to sleep. That's something that you can do. You can give yourself time to sleep. You can do what's called sleep hygiene. I don't like that word because it makes it sound like you're dirty if you don't do it, and so it's not-- anyway. You can do things that will help you fall asleep. You can have a room that's dark and cool at night, but then you want light during the day. You have to talk to somebody else about light pollution, about noise pollution, about bad shiftwork,
35:38 about adequate support for families so that people have to work multiple jobs or don't have support for children or elder care. That's outside most individuals' ability to do something, and so it becomes a societal problem or a political problem, in addition to what people can do. Once again, I don't want people to feel hopeless. I want to say that you-- suggest that you try and do what you can do, and that includes trying to go to sleep, maybe not doing social media, maybe not watching as much TV, maybe not staying up late doing something else, but prioritizing sleep over some other behaviors. Now, I'm really trying really hard not to sound like a nag
36:23 and telling people they shouldn't have fun. I'm not telling people they shouldn't do what they want to do. You asked me, what can I do so that people can get more sleep? And one of those may be that some evening activities or very early activities you don't do so that you can get more sleep. I am not telling people what to do. I'm making suggestions about what people can do so that they can hopefully sleep more and better. Does that make sense? Did I say that right without sounding like a scold? No, not at all. So just following on from that, is there something that we can do collectively through advocacy, perhaps, as a society to reframe sleep from something we fit in around everything else that we have to do in our lives, to really seeing it as a long term investment in our own health?
37:09 And how can we align that with maybe policy making about health interventions, about school start times, maybe Daylight Savings Time? Is there a role that we can play to advocate for societal change in this area? That's a great question, and I don't know how to do that because I'm not somebody who knows about advocacy or how those work. I'd like to think that advocacy work, certainly the people about start school time later, have had success in some areas of the country, which incidentally, if you move to permanent Daylight Saving Time, you would lose those success. So there are people. The Mothers against Drunk driving were successful, and we've actually-- some people have tried to contact
37:54 them to make Mothers Against Drunken Drowsy Driving or Drowsy and Distracted Driving. So seatbelts was another successful public health campaign. Cigarette smoking was another successful-- anti-cigarette smoking was another successful campaign. And of interest about cigarette smoking, as somebody pointed out to me, Michael Twery of NIH, that there was never a randomized controlled trial of cigarette smoking. There was just a preponderance of evidence. And so while I have occasionally said there's not enough evidence to know that exactly, there may be enough evidence that we already have that we don't need to know another style. Or we can say, no, kids shouldn't go to school so early, or we should try and fix A, B, or C,
38:39 but I don't know how to do that kind of advocacy. There are other people who know how to do that, and hopefully some of those are on this, or somebody knows somebody who knows how to do that. That's a great thing. I just don't know how to do it. We'll give you a pass on that one. Thank you. So you mentioned drowsy driving and you also mentioned the Colloquy article where that your own drowsy driving kind of leads off that article. Can you just share a little bit about the difference between having enough sleep and feeling alert? Sometimes you think you are-- you're like, oh, I've had enough sleep. And then you undertake something like a long drive at night and then all of a sudden, you find yourself going off the road, as has happened to you.
39:25 But I think we have-- not tired and alert, maybe, are two different things. And maybe you could, if you agree, maybe share a little bit about the differences. The brain is really bad at self-assessment. So we did a number of studies. Me and others have done studies where we gave people insufficient sleep and asked them how tired or how alert they felt. And so if you have a graph where this is how well they do like on a performance test, just pushing a button when the screen changes or adding two numbers, and this is what it looks like, how sleepy or alert they feel, for some people it looks like a sneeze, just like it's all over the place. You want to have this nice line that says, I'm more alert when I have fewer errors or whatever. For some people it just looks like a sneeze, and it's certainly worse if people haven't getting enough sleep, which is most of the population.
40:12 So if someone tells me that they're tired, I believe them. But if they tell me they're alert, I don't necessarily believe them. So going by-- and part of that is the study that was actually done at the University of Pennsylvania, where they tracked across time how sleepy people felt versus how many days they had gotten enough sleep. And it looked like this. They said, I feel-- for the first two or three days, they said, I feel more and more tired. And then they didn't change, even though by all other criteria they were getting tireder and tireder, because their reaction time was slower or other things were happening. And so it may be that how sleepy you feel depends on your comparison to how sleepy you felt before. And one example is sometimes people who have had sleep apnea
41:00 and had bad sleepiness and are treated for sleep apnea, they will say, oh, I'd forgotten what alert felt like. This is what alert feels like? Oh, I'd forgotten that. You can't remember what feeling alert looks like. And indeed, another study I had done where we in the lab purposely not giving people enough sleep and then gave them enough sleep to look at some of these effects, one of the people said when they were getting enough sleep, say, can I go back and change all my questions before, because I had forgotten what it felt like? And I said I felt fine, but I no longer remembered what feeling fine looks like. So unfortunately, people's self-assessment, even if there's no gain to it, like, oh no, I only have to drive two more miles and get home or oh no, I'm the person that's going to do this task that's so exciting, is not good, because the brain
41:48 is very bad at self-assessing. And as I said, you're not aware you're asleep until you've woken up, which was so obvious to me when I fell asleep at the wheel because I was highly motivated. It wasn't that I wasn't motivated, and I know how to drive. And so it wasn't that my skills wasn't there. It's just I was tired and I thought I was alert enough to drive. And there was even somebody else in the car who could drive. It's not like I was doing it all by myself. Anyway. Yes. We've had a few questions come in about technologies. So there are apps and wearables and other technologies that can help track our sleep or keep
42:35 track of even the cycles of sleep that we might be in. Can they truly help us get better sleep, or do they just give us more information to perhaps persuade us to go to bed earlier or eliminate some of the busyness of our daily lives in order to get good quality sleep? What can wearables and other technologies help us in terms of-- how can they help us in terms of sleep? So the answer to that depends on the wearable, and it depends on the software version of the wearable, and it depends on what you want to use it for. So I can't answer globally, and I certainly wouldn't say that this particular software on this particular product is what you can use, because it might be good for one thing,
43:21 but might not be able to diagnose your sleep apnea. If your wearable helps you get more sleep, I'm all for it. By definition, it is not measuring your brainwaves, which is where sleep happens. It is measuring downstream physiology. So when you're in different stages of sleep, your breathing is different and your movements are different. But it is not actually measuring brainwaves, because you can't measure brainwaves from the wrist. So all the studies about sleep are scored by brainwaves, and health cannot necessarily directly, though they may eventually, but they cannot be directly changed. I absolutely want to get to, I think, a burning question that everybody has, which is about any advice for someone
44:07 to improve their sleep and any sleep hacks, what's the effect of naps, and all that. I want to get to that question in just a second, but I want to pivot slightly for a moment, if I may, because I'd like to talk about you for a second. You've done an enormous amount of mentoring, both within the Harvard community and internationally, as I mentioned in my introduction. You're responsible in part, anyway, for mentoring the next generation of scientists, and the pipeline of research and lack of government funding might be changing that. Can you talk a little bit about your work mentoring the next generation of scientists, sleep scientists, or scientists in more general, a little bit about your mentoring? And then do you see that changing now as a result of government funding freezes? So thanks for that question.
44:52 I love doing mentoring in patient-oriented research. You can't teach how to do patient-oriented research just in a classroom. And in order to teach people how to do this, you actually have to sit with them and talk about what is their question. Several times you asked me something, and I've redefined the question so that I could answer it. So somebody will come to me and say, I'm really interested in whether x affects y, and then we have to sit and together decide what is the question, what is the best way of answering the question. What is the methodology for gathering the data? What data point, what kind of data do you want to gather? How are you going to analyze the data? And then how do you write a grant, whether it's an NIH grant or some other grant? How do you respond to criticisms? How do you implement your ideas? How do you then write papers and get them reviewed?
45:42 And that all requires one on one mentoring, which I love doing, because all these great young people have great ideas in areas in which I am not an expert. And if I can just help them get over the hump about how to communicate their ideas, how to refine their ideas, then I can help them succeed. One of the worries about the current funding is that there is less funding for junior investigators, and if we lose them now, they may not come back into the field. And how will that affect-- or if we lose them to another country, they might not come back. They might not come back to the United States, or other talented people might not be coming to the United States. And how will that affect us long term? You can't just say, oh, now, three years later, OK,
46:28 now there's funding, and expect people to change back. It's just like longitudinal data requires collecting the data all the time. You can't just dump it, drop it, and come back. I'm happy to help anybody that wants to work with me, if I can. And once again, I'm not a politician. I don't know how to affect federal funding or statewide funding. I can just-- happy to work with people so that they can present their ideas in a way that will hopefully get funded so they can do what they want to do, and then how they can present their ideas in a way, when they go to a meeting or when they give a talk or something else like that. So I would like to say, if you're interested in supporting junior faculty, you should also potentially support the senior faculty who are supporting the junior faculty,
47:15 and enabling them to do what they want to do. How's that sound? That sounds great. All right, now let's get to the last question. So people are definitely looking for some sleep hacks. They want to know about naps and sleep routines, any interventions that we can do. So all of that is to say, let's end on what's your best advice for someone trying to improve their sleep and maybe improve aspects of their health through improved sleep. So I usually say, if you want a nap and you can nap in a safe place, you should nap. There's no evidence that people can sleep when they're not tired. You give me a piece of chocolate cake and I can eat it even if I'm not hungry,
48:02 but there's no evidence that you can sleep when you're not tired. And indeed, I did a study, the same study that we looked at the night to night variability. After people had gotten enough sleep, we did a study where we looked at younger and older people and we said, sleep at home all you usually do, just sleep whenever you need. You just can't have caffeine for the week before you come in, because we're not going to give you caffeine in the lab, but sleep all you need. And then we brought them into the lab. And the first night in the lab, they slept at their usual time in duration. And then we did something called the multiple sleep latency test, where we had people try and nap to see how sleepy they were. And the people who slept at home, less at home, fell asleep more quickly on the naps, as expected. And then we gave them a couple days
48:49 of this 16 hours of sleep opportunity, which is 12 hours at night, awake for four hours, sleep for four hours, awake for four hours. And during those 12 hours and four hours of sleep opportunity, they were in the dark. They weren't allowed out of bed. They had to try and sleep. The average amount of sleep on the first 24 hours with 16 hours of sleep opportunity was 12.5 hours. People said no, no, I only need six or seven hours. Everybody slept more than they did before. And it gradually asymptoted down to that eight-ish hours. So the first thing is to give the first advice is to give yourself extra time for sleeping. And certainly, during the beginning of that protocol, people were definitely sleeping during the naps. We gave them nap opportunities because we were afraid that they'd maxed out how much they could sleep at night,
49:36 so we wanted to give them daytime sleep opportunities. So if you can sleep during the day and it's safe for you to sleep, you have a safe location, then if you need to sleep during the day, sleep during the day. In terms of your ability to sleep, it's usually better if you can keep a somewhat regular schedule. Don't try and go to sleep at 2:00 AM one night and 10:00 PM the night before, and there's increasing evidence that kind of variability actually may also be bad for your health in large studies. Now, that's different from sleeping in on weekends. You should sleep in on weekends. That kind of variability is good if you-- but I'm talking about one night to another night variability may not be good. So as I hopefully mentioned before, start-- if you're having problems sleeping, caffeine and alcohol can affect your sleep.
50:21 Start preparing yourself for bed. Try and sleep approximately the same time in a dark room, where it's cool. Sleep as long as you can. There's no shortcuts that I know of. You have to give yourself an opportunity and hopefully a good environment in which to sleep. And unfortunately, not everybody has that, as we mentioned before. But there's no shortcuts that I know of to help you sleep more effectively except not caffeine or alcohol or whatever. But there's no way to shorten it. There's been no studies that show you can teach yourself to sleep less. Behavior change is really hard. Yes yeah. I think naps-- with naps, I'm wondering if you take too long
51:11 a nap, does it then affect-- Absolutely yes. Well at night. Is there something there? So I'm sorry. I should have said that. If you take longer than around a one hour nap, 45 minutes to an hour, you will have really bad what's called sleep inertia, this groggy feeling when you wake up. And so during the day, we usually recommend that you don't sleep more than 45 minutes because the sleep inertia can be really bad. And if you do take a long sleep during the day, it may affect your ability to sleep at night. So the question is, why do you need to sleep during the day? Are you not getting enough sleep at night? And so it can become this sort of bad cycle where you sleep a lot during the day and then you can't sleep at night. The usual preference is if you have a daytime active lifestyle or whatever, it's trying to sleep as much and as well as you can at night and have a relatively short nap, and only if needed.
51:57 You still have some sleep inertia when you wake up during the morning, but it's not as bad as if you sleep a lot in the afternoon or in the evening. And when I say sleep a lot, falling asleep on the sofa is sleeping. I'm talking about all the sleep that happens over the 24 hours. Now, I realize that some people fall asleep on the sofa because for whatever reason. But I'm just saying, count that into how much sleep you're getting over the 24 hours. Not just sleep in bed, but if you're falling asleep on the sofa watching TV, that's still part of the amount of sleep you're getting over 24 hours. Does that make sense? It does, absolutely. And I'm sorry that we have to cut this conversation off as we're coming to the end of the hour,
52:43 because this has just been fascinating. Thank you so much, Dr. Klerman, for being you. I hope I was clear. I hope I was positive. And thank you very much for your interest. Yes. I want to thank all of the folks who submitted questions. I'm sorry if we didn't get to your question today. And I also want to invite you to our next webinar, which will be taking place on February 11, "Can ChatGPT Plan Your Retirement," with Andrew Lowe. So if you've enjoyed this program, we hope you'll join us again for another Harvard Griffin GSAS event. And again, Dr. Klerman, thank you so much for sharing your expertise, your wisdom, your advice, your insights with all of our alumni.
53:29 And we're just very grateful to you for the time and the information you shared with us today. So I hope everyone has a wonderful rest of the day and a very restful and full sleep tonight. I hope Dr. Klerman helped you think about your sleep and prioritizing that for your long term health. And so, Dr. Klerman, thank you and thank you, everyone, for being with us today. Thank you.
