Best of: The future of sleep

0:00Jamie Zeitzer:Hey everyone, it's your host here, Russ Altman from The Future of Everything. This coming weekend marks the start of daylight savings time, where for many of us, we spring forward an hour and add one hour to the clock. While the extra evening daylight time in the spring and summer is great and leads to very many beautiful evenings, this time change can mess with our sleep cycles. Last year, I sat down with a sleep expert, neurobiologist, Jamie Zeitzer, and we talked about practical strategies to deal with sleeping problems. As we approach this transition to Daylight Savings Time, it's the perfect time to revisit this conversation.

0:34Jamie Zeitzer:I hope you'll add this episode to your playlist and take a listen and think about what this might mean for your sleep. And of course, I hope you sleep well.

0:49Jamie Zeitzer:Well, we all know about sleep. We all know that it's critical. We know that it's annoying not to get enough sleep, and it's great to get a good night's sleep. but the frequency of folks who have trouble with sleeping is remarkable. One of the things that they do is they worry about their sleep. We're going to find out that worrying about your sleep is a great way to make sure that you don't get great sleep. But what about medications? What about wearables? My watch can tell me how well I slept last night, but guess what? I kind of already know. Well, Jamie Zeitzer is a professor of psychiatry and behavioral sciences at Stanford University.

1:22Jamie Zeitzer:He's an expert at circadian rhythms, bad sleep, good sleep, and how to optimize sleep. He's going to tell us that wearables don't work. There are some medications that sound pretty promising and don't worry about it as much as you are because that's contributing to the problem. Jamie, what made you decide to devote your professional life to the study of sleep? Probably the old adage of, you know, physician helped myself. Never been a good sleeper, always had problems. Actually came in through a back door. I was trained in circadian rhythms, but found that sleep paid the bills better. Okay. Well, that leads right to what I wanted to ask you about, which is two things.

2:06Jamie Zeitzer:Why do we sleep and how is it related to our circadian rhythms? And maybe you should define for those who haven't thought about circadian rhythms very much. What are they and how do they relate to sleep? Sure. So circadian clock, something I didn't hear about until graduate school. So if people haven't heard about it, that's okay, though it is definitely more out there right now. These are intrinsic 24-hour rhythms. I find them particularly appealing. They are endogenous to an organism, and you find them in every single organism that has ever been studied on the planet Earth. So there's obviously something incredibly important about them if throughout the evolutionary tree you see them.

2:43And these are basically the key to these rhythms is that they allow you to anticipate changes in the future. As opposed to responding to the environment, you can anticipate them. And so one of the obvious anticipations that we have as humans is sleep. And so it's very much intimately involved in the timing of sleep, when we sleep and how we sleep.

3:02Jamie Zeitzer:So it sounds like from what you're saying, I'm kind of it's kind of implying to me that circadian rhythms might have lots of other uses to the organism other than telling us when to go to sleep and when to wake up. Absolutely. They're basically involved in pretty much any physiologic process. I mean, the vast majority of them have a circadian component. The real question is, what is the magnitude of that component? Not if it. And in fact, when people show like, oh, there's no circadian component, I'm like, wow, that's really important. because it means that you have to be up all the time. There's no anticipation for it.

3:37And so everything, you know, if you look at immune system, if you look at breathing, heart, you know, diet, every aspect of your physiology, there's a circadian component.

3:45Jamie Zeitzer:Okay, great. Okay. So, and now let's go to sleep. And I kind of buried it, but like, do we understand why we sleep and why it's critical? No. Okay. Thanks very much. That was Jamie Zeitzer. There you go. So, I mean, you know, we have ideas about what happens during sleep. You know, what exactly, why is it important? I mean, by far, if you take a look, by far the biggest effect size about losing sleep is you feel tired. and it's not i mean it's it's more than tenfold bigger than any other like cognitive effect like basically is your cognition is good if you don't get enough sleep no is your memory is good no is your metabolism is good no but all those pale in comparison to the fact that you feel tired right um and so you know what is sleep doing well it's doing a lot of things you know i i think that there's no singular thing that it does it basically it prepares us for being awake and anything that can be optimized during sleep while we're not awake and gathering information.

4:47That's kind of what happens there.

4:49Jamie Zeitzer:So you said earlier that part of the reason you entered the field is you have problematic sleep. And I want to get into that. Well, perhaps not your personal sleep situation, but the issue. But I will also just disclose that I feel very lucky to be, I don't know what the word would be, but gifted would be the only thing I can think of. And it's been an incredible asset to my life. When I get nervous about things, I actually go to sleep instead of like staying awake. And it was extremely adaptive, like as a student and whatnot. Okay. Enough of the biography. I know you've studied a lot about light and there's a sense that we all have that the circadian rhythm in some sense is kind of synchronized with the sun.

5:29Jamie Zeitzer:And so tell me about the role of light and particularly in sleep. Sure. So where the circadian clock in humans on average is a little longer than 24 hours, around 24.2 hours. So it has to synchronize to a 24 hour day. How does it do that? Mainly through light. And so basically your light exposure is dictating where the circadian clock is placed. The most obvious place that you experience this is when you travel across time zones, you go into a new time zone. How do you adapt your internal clock to the external time that you're living on? That's through light exposure. So the light exposure is basically dictating where the circadian clock is positioned.

6:06And therefore when you're sleeping, when you feel tired when you feel alert.

6:10Jamie Zeitzer:And is it sunlight? Is that what we need? Are there certain waves of light? I know you've looked at flashing lights. This is all very interesting. Yeah. So basically anything you can see can impact the clock. And it's just a question of magnitude. If you are completely optimized, so you've been in a dark environment for a long time, even fairly dim light, just like a few candles worth of light can impact the clock. But in general, in most adult humans, you're talking about room light being effective and outdoor light being about twice as effective. Even though outdoor light is more than tenfold brighter, there's a compression of this information.

6:52But that being said, room light, it's about half as important as outdoor light. So even what you're getting in a standard office environment, home environment, can be very impactful.

7:02Jamie Zeitzer:And does that have any implication for like optimal? So I think of room light as a little bit more orange, a little bit on the red side of the spectrum. I think of sunlight outside as a little bit more blue. Does that imply if we're spending time, you know, a lot of us are in offices that we don't get to go be outside all day. Does that make implications for what kind of lighting we should or should not be using in our internal environments? Yeah. So the circadian clock is definitely optimally sensitive to the shorter wavelengths, blue light. And that's because basically how light information goes from the outside into the circadian clock is a combination of your rods and cones, which again, you see things with, which are more optimized in in toto to green light but then it also uses this substance called melanopsin which is a opsin it's basically it's a protein in the eye that can also respond to light and that's blue sensitive so this is why when you hear a lot about blue light that's the kind of the concern now again any light can have an impact but blue light photon for photon is more impactful so when you're inside the real thing about being inside and again after the pandemic so many people working from home.

8:21The real thing is that you need to create a contrast, right? So basically, the brain is, and the circadian clock is really good at adapting to your light level. So even if you were, say, living in a cave all day, if you had five minutes of light, that'd be totally fine. Right. But you need a contrast. You need dark and you need light. And so if you're basically inside all day in an office and then you're, it's a home office and you're into the same lighting throughout the evening, there's no contrast. It didn't know that that was day and that this is night. And so the, really the thing that people have to pay attention to in terms of working from home, things like that, is that they have to create this contrast.

9:03And that contrast might be, have better lighting in your office. So basically brighter lighting. I mean, we found that even if you just increase the brightness of your lighting during the day in a home office, that's sufficient. Or go outside, which is good for a number of reasons. But go outside for a half hour in the afternoon, like three o 'clock in the afternoon, ideal time to go outside. You get the light there. And the other thing that that does is that it also minimizes the impact of light in the evening. So the light, how the clock responds to light, as well as many other kind of impacts on the brain, it's a relative thing.

9:43So it's not just looking at how bright it is. It's how bright it is compared to what you were getting before. So if you're inside all day, there's no contrast. If you go outside for a half hour in the middle of the day, you get, well, nice California weather. We're getting 80 ,000 lux outside. You come back inside and you get 50 lux. All of a sudden that 50 lux isn't so bright. But if you're getting 50 lux all day and then you're getting 50 lux in the evening, that appears brighter to the system.

10:06Jamie Zeitzer:Okay, so I do want to go to the issue of people who are having problems with sleep. Yeah. And I think it's going to be related to a lot of these things. And, you know, we're all getting advice about, you know, if you're looking at your phone at midnight, you should be looking at your phone with an orange light and not with a blue light. And I don't even know if you want to comment on that at this point. Oh, sure. No, absolutely. A lot of things do, but this particularly drives me nuts. So if you are, again, inside all day long, don't get any bright light. Can that light from your phone impact your brain?

10:42Sure. Absolutely. I mean, physiologically speaking, you keep someone dim light all day and then you give them a phone at night, it will impact it. The vast majority of people, though, don't do that, right? They're getting any degree of light that would really minimize that light. So the problem is that when you say, oh, I've got the orange filter on my phone, now I can do whatever I want. No. It's like you're doing things like you're checking your email, which is stressing you out, or you're on an app that has been optimized by psychologists to keep you on the app. I've got this great clip that I love playing for classes here, which is of Reed Hastings, who's the CEO of Netflix.

11:19and during a corporate earnings call, and this was several years ago, he said, our biggest competitor is sleep. Oh, my goodness. And he wasn't kidding. It's because you've got the next episode button and you're just kidding. Next episode, next episode, next episode. And so you don't pay attention to sleep. So blue light, light filters on phone, do they work? Yes. If you're inside all day, they're nice. But by far, the much bigger thing is the content, what you're experiencing, how it's impacting you. If you're checking something out, you know, and you're stressing out like, oh my God, everyone else is having so much fun.

11:55I'm not having fun. Yeah. That's going to keep you awake. Right. Or, oh, look at all this work I have to do. Going to keep you awake. Oh, politics. Wow. Yeah. That's definitely going to keep you awake.

12:04Jamie Zeitzer:Right. So perhaps the blue orange thing is in the noise of all the other stuff that's happening. When you look at the effect size, it's not even close. I mean, the only good thing that it really does is that it provides kind of like an inverse alarm clock. It reminds you it's time to go to bed. Like when your screen automatically changes color, you're like, oh yeah, it's 11 o 'clock at night. It's time for me to go to bed. I lost track of time. So in that sense, it can be a helpful psychological cue. But in terms of its actual effects in the brain, it's really doing quite little. Okay. So let's go to problems with sleeping.

12:41Jamie Zeitzer:It is so common. I'm aware of it because as I said, I don't have problems. And so I'm maybe sensitive to hearing how many people are struggling with it. It's a topic of conversation. What can you say about it? Like, what are the sources of this? What I am impressed by is when you ask, as a physician, I'm a doctor, I can ask somebody, how's your sleep? I do not have to explain what it means. They know if it's good or bad or middling. And so tell me about sleep problems and how we should think about them. Yeah. So it's good that as an MD, you actually ask people that question because most MDs do not want to ask that question because then they'll get an answer and they don't know what to do.

13:20Right. Right. So I've got to document that. So and Doc, can I have a pill, please? Exactly. Because that's what people want. I mean, they just want they want an on off switch. We don't have that. There's so there's been a lot of concern about sleep. There's been a lot of, there've been many things published in the lay press books telling us how terrible it is to lose sleep. I don't happen to agree. Now, I'm not saying that the data are wrong, but I don't happen to agree that scaring people into getting more sleep is actually an effective way of getting more sleep. What it does is it makes them more anxious about their sleep.

14:03And the only thing worse about not getting enough sleep is not getting enough sleep and being anxious about it. Yeah.

14:09Jamie Zeitzer:Yeah. That's worse. I mean, the stress that you're experiencing, that's doing far more damage. Honestly, losing the night of sleep or not getting great sleep, it's more like a lottery ticket. Very long odds. And you're talking about like telling someone who's 25 years old, you know what, you should get better sleep because in 30 years, if you don't get good sleep now, you're going to have like a 3 % increased risk of getting diabetes. I mean, it's stupid. I mean, that's not going to actually change people's behaviors. So there's a lot of anxiety and that's causing problems. We can talk about wearables.

14:48They don't work. Oh, wow.

14:51Jamie Zeitzer:Okay. So you went right to the wearables and like, you know, my watch every morning is telling me exactly how much time I spent in each of these phases that I don't really understand. but it's very impressive. Yes, it's nice, but in you, it's probably actually reasonably accurate. In bad sleepers, it is completely inaccurate. And there are a number of reasons for that. But the biggest problem is that even if it were 100 % accurate in everybody, it's decontextualized information. It makes people anxious about their sleep, especially if they're getting good sleep, fine, great. But if you're getting bad sleep and it's actually really saying, well, you didn't sleep well last night.

15:32You know, you didn't get a lot of deep sleep. You got too much N1 sleep. What am I going to do about that? Like now you're just making me anxious. Like before I just woke up and I was tired. Now I'm waking up and now I'm anxious. So it's not particularly helpful. And that's something, you know, that I hope in the future, basically, this is one of the things that I think that we need to get to is not only making that data accurate in people who are bad sleepers, but also then contextualizing it in terms of what you can do.

16:03Jamie Zeitzer:Yeah. Actionability is always kind of on, on, that's what, that's what the physicians would want. That's why they would, they would ask more if they had a toolkit to actually be helpful. Exactly. Look, now there are, there are standard kind of interventions that work quite well. CBTI, cognitive behavioral therapy for insomnia, works really well if people are willing to do it. It's not talk therapy. It's not like how your mom screwed up your sleep in your entire life kind of thing. This is more on like, okay, here are some tools that you can use to get sleep better. And the amazing thing about it is when you look at the objective measures of sleep and someone who's been successfully treated, like they had bad insomnia and now they say they're fine.

16:45Their objective measures of sleep really don't change that much. What changes is their perception. They basically, you teach them not to care about their sleep so much. And so if it takes you, for example, if it takes you a half hour to fall asleep, that would be considered a long time. But if it doesn't bother you, that's not insomnia. Clinical definition of insomnia and all of the international definitions, no numbers, right? So it's not about how long it takes you to sleep. If it takes you 10 minutes to fall asleep, which is totally normal, but you're anxious about that, that's insomnia. Okay.

17:20Jamie Zeitzer:So there's a functional element to these diagnoses, which actually sounds like the right answer. Yeah. I mean, so it's basically saying like, if it doesn't bother you, okay. You know, and really there's, there's been a move, you know, people have for a long time, really kind of dichotomize sleep. You have good sleep or bad sleep, you know? Um, now we understand that there's, there are people with good sleep and there are, and there are people with pathologically bad sleep, but it's a bell curve and there are different components. Duration is just one of them. You know, how, how regularly you go to sleep like if you you might have like when we study college students they're wonderful to study because um i i often went when i when i lecture to them i'll thank them because i i say because you do things to your sleep that we study that ethically we're not allowed to ask the ethics board would never let us do what you do to yourself no in a million years it's like so what i want you to do is sleep three hours tonight but go to sleep at 2 a.m then tomorrow night i want you to not sleep at all and then the next night i want you to go to sleep five hours earlier but sleep 10 hours it's like you can't do that like there's all sorts of data saying how bad that is for you but people do this so you know and they very rarely have you know insomnia i mean many you know there are many college students who do but they're usually so sleep deprived right there's no insomnia i mean we in fact have studied in the past we did a a modeling study looking at the impact of caffeine and basically found that for most college students, caffeine has no impact.

18:49Like they're having like 600 milligrams of caffeine before they go to bed and fall asleep instantly because they are so sleep deprived.

18:56Jamie Zeitzer:Yes. My daughter is a resident. She's a medical resident and she's had sleep problems in the past per her own report. But I asked her about her sleep during her residency and she said, that has gone away, dad. If I see a bed, I'm asleep. See, there you go. This is where gurneys all of a sudden look like comfortable, you know, sleeping positions. This is the Future of Everything with Russ Altman. More with Jamie Zeitzer next.

19:30Jamie Zeitzer:Welcome back to the Future of Everything. I'm Russ Altman and I'm speaking with Jamie Zeitzer. In the last segment, we talked about some of the basics of circadian rhythm, sleep problems, and worry. In this segment, we're going to touch upon medications, and we're going to talk about some easy do's and don'ts that can help you improve your sleep if you're not happy with it. We were just talking about these college students that you talked to, and the fact that you can kind of, my words, not yours, you could hardly pay them to have more bizarre sleep habits. So what kind of things do we learn from those students and teenagers and people who are at the extremes of like testing their sleep ability?

20:09Yeah, so we use it to our advantage. Basically, what we do is we, when they have these kind of weird schedules, we're able to then look and see what is the contribution of circadian rhythms and what is the contribution of sleep. So in normal humans that are regular sleepers at all, when your circadian clock is timed, it's almost always at the same time relative to sleep. It's always signaling for sleep when you're asleep. In college students, sometimes it's signaling for sleep when they're awake, sometimes it's signaling awake when they're asleep. So basically, it's called basically a desynchronization of these two systems.

20:48So it basically gives us an opportunity to study what the contribution of this. So, for example, we're right now we're just finishing up a study where we're looking at how sleep and circadian rhythms in the menstrual cycle impact injury risk in college aged women. And so basically these have been studied independently, but these are not independent factors. So the question is, well, can we use this and kind of tease it apart? So we're using it basically as kind of a scientific tool.

21:12Jamie Zeitzer:Yeah. Now, of course, it would be great if they slept better. But, you know, students are busy. They've got fun lives as interesting things. And so we're letting them do that and then trying to figure out like how to adapt afterwards. Really interesting. So that made me think that is it something about college or is it that age group? So if I look across the world at people in that age range, let's say 18 to 22, are they kind of always a little bit wacky with their sleep or is this a phenomenon about the college? I think it's a combination. I think at that age, basically, you have the independence to do this kind of stuff.