Take a Nap! Change Your Life | Sara Mednick | Talks at Google

Please help me welcome Dr. Mednick.

Thank you very much for having me at Google. It's a real, real pleasure to be here. And I just want to start with a disclaimer to say that I know you guys are extremely overworked. So if any of you take this opportunity to take a little nap, I will not be offended. Just go right ahead and hopefully your neighbor will just nudge you if anything really exciting happens. Okay, so first of all, why do we need a book about napping? Well, one reason is that comes from the National Sleep foundation, which is a non profit organization that studies our sleep and how sleep deprived we are and finds that about 40% of Americans are sleeping around 6.7 hours at night when we should be getting around 8 hours. So that doesn't just happen to people like you who are working really hard, but it happens to kids and middle age and older adults as well. So there's definitely children are shown to be sleeping an hour less than they should be and it spans the ages. This also spans the sexes. So men have always been researched a lot in science and now women are actually becoming more of a subject to look at in science and finding actually that women are really reporting sleep troubles at really high rates. 67% of women reported trouble sleeping three nights or more a week. And of course, everybody who's ever had a child knows that there's the whole issue of being a parent and never sleeping and looking like you're on a rotating shift and that can probably be the worst thing for your cognition at all. So what's the cost of sleep deprivation? Well, there's definitely health costs. Sleep deprivation has been shown to decrease to increase your risk for heart disease, increases high blood pressure and actually about five nights of say only sleeping six nights a week can actually raise your insulin levels so that you look like you're at pre diabetic levels also increases your stress levels and puts you at risk for depression. Safety. Of course there's smaller things like car accidents which are fatal and terrible, but also really large global problems to the environment such as the Exxon Valdez and Bhopal and a lot of these major accidents that in some part have been due to somebody really just falling asleep on the job. There's also the Department of Labor has shown that there's a 4% loss even just entering every day, that if you're sleep deprived, you're already bringing in a 4% loss to your productivity. And of course education cognition in general decreases. And I'm going to show you a bunch of evidence about this. So now one question is, is everyone a victim of sleep deprivation or are some people more immune than others? And I'm sure a lot of people here probably think that they can get by on less sleep. And I know in grad school I definitely thought the same thing. And of course, probably the worst culprits of them all are the doctors and nurses, because they have a culture of really not sleeping and learning how to get by on very little sleep. But in fact, a recent study that came out of Harvard was showing that comparing doctors who work 30 hour shifts versus doctors who work 10 hour shifts, and those 30 hour shift doctors were making 700% more errors. So that's a kind of a chilling number, especially if you think about the errors that they could possibly be making. Nurses as well have been shown to be extremely dangerous. Once they get out of work on the road, they get into more accidents. Soldiers as well. One pretty important quote that I heard from a general was saying that sleep deprivation is one of the major killers in Iraq right now because there's just so many errors that are occurring that could very well be due to just people being very too tired to think about what they're doing. And politicians, of course, the people who are making the laws happen. So the idea is, what are we supposed to do? Because what doctors are saying is that we should just sleep more. And as all of you know, it's really hard to find an extra hour in the nighttime to sleep because we're already basically maxed out. And of course, there's a whole bunch of education about increasing our sleep health that really is very important. Right. We need to figure out that you shouldn't be sleeping with the lights on, that you shouldn't be sleeping with a TV on, that all these different. That you should turn off your computer and just not do anything else in bed. But just a couple very important things. And those are things that we'll learn. But what really happens is that instead of sleeping, we actually go to some pretty bad coping mechanisms. First is caffeine. I mean, everyone drinks caffeine. About 90% of the population drinks caffeine. But then you also, sleep deprivation can lead to an increased risk and use of stimulants. And definitely people who are sleep deprived are shown to reach for more high fat and sugary foods because you know, your body is probably in a state of emergency and thinking, why am I so sleep deprived? Something bad's going to happen. I better get a lot of energy from really bad food. So, you know, you just Kind of nasty spiral. So I'm just going to move on from the horror story and then sort of tell you my own little story about how I actually got to studying this kind of stuff. I was in grad school, wandering the halls of William James, totally sleep deprived as everyone usually is, and looking for a thesis. And I ran into a lecture by Robert Stickgold and he was doing stuff, looking at memory performance after a full night of sleep and showing that, well, you need at least six hours of sleep and to show improvements in memory. And I thought, well, that's really interesting. I want to study something like that. And then when we started talking about it, I realized that in fact, all those people who I knew who were nappers, I wasn't really a napper myself, but all those people who were nappers really swear by their naps. And it doesn't really jive with the nocturnal sleep literature. How is it that a nap of 20 minutes or an hour can make you feel really, really good when you need at least six hours to show any differences in performance? So that was why I started looking into napping as a thing to study. And while I was actually doing this research, I decided that I am, much like Kiki was saying, sort of guilty of this idea that I had this really bad thought that napping was for lazy people. And one day when I was falling asleep at my desk, I just decided to give it a try. And it was a great experience. I went into my friend Jay's office and I slept down on the couch. I just crashed out and I woke up an hour later and I was able to work for the full until 2am without falling asleep at all and feeling really great. And I thought, this is data works, it's really cool. So I started actually napping regularly in the lab. And then the entire lab actually started rotating on this couch. And we stole the couch from Jay and moved it into this kind of common area where we could turn off the lights and not have any disturbance. And then people all hours started sleeping on this couch just to let themselves get to a place where they could actually continue working and have much more stamina through the day. So that was pretty exciting to have kind of the first real nap positive workplace to go to and create. So I'm going to go over the stages of sleep. This is kind of just sleep 101 and I have a little pointer here. Let's see. So across the. Can you see here on this. I'll be on this one over here, the far one one. So across the Top over here, you see this is the nighttime. So 11pm to 6am and what these colored bars represent are the different stages of sleep. And what happens is there's actually you go through a normal night of sleep, you'll go through about four or five, what's called sleep cycles. And a sleep cycle means that you're going to pass through all the different stages of sleep. And I have them down here. Well, there's waking, of course, and then there's also stage one, stage stage two, and slow wave sleep. And then once you wrap back up to stage one sleep, it turns it to be REM sleep, actually rapid eye movement sleep. Over here is the EEG output, which is just the electrical signaling that's going on in your brain during these different stages of sleep. And as you can see during waking things are really busy. It's a very hectic stuff up there going on in your brain. Lots of brain areas are speaking all at the same time. And you're basically multitasking. And then once you fall into sleep, one of the biggest metabolic changes that you ever really experience happens every time you get to sleep. And everything really starts to slow down and quiet down. And you can see as you go from stage one into stage two, things start to slow down all the way into slow wave sleep. And this is what's called delta waves, which is basically your whole brain is speaking in synchrony at a very slow rate. And once you get through slow wave sleep, then you wrap back through stage two and you get up to REM sleep again. And REM sleep actually looks very similar to waking because it's a very busy time in your brain. But the only thing that's different about REM sleep from stage one is that you're actually paralyzed and you have these rapid eye movements. So what you might notice going across the evening up here on the top of the screen here is that there's a lot more slow wave sleep in the first part of the night. And then slow wave sleep starts to taper off and then you have an increase in REM sleep. Now this is actually a very important phenomenon that. So the idea is what are we supposed to do? Because what doctors are saying is that we should just sleep more. And as all of you know, it's really hard to find an extra hour in the nighttime to sleep because we're already basically maxed out. And of course there's a whole bunch of education about increasing our sleep health that really is very important. Right. We need to figure out that you shouldn't Be sleeping with the lights on that you shouldn't be sleeping with a TV on that all these different. That you should turn off your computer and just, you know, not do anything else in bed. But just a couple very important things, and those are things that we'll learn. But what really happens is that instead of sleeping, we actually go to some pretty bad coping mechanisms. First is caffeine. I mean, everyone drinks caffeine. About 90% of the population drinks caffeine. But then you also. Sleep deprivation can lead to an increased risk and use of stimulants. And definitely people who are sleep deprived are shown to reach for more high fat and sugary foods because you know, your body's probably in a state of emergency and thinking, why am I so sleep deprived? Something bad's gonna happen. I better get a lot of energy from really bad food. So, you know, you just kind of. It's a nasty spiral. So I'm just gonna move on from the horror story and then sort of tell you my own little story about how I actually got to studying this kind of stuff. I was in grad school, wandering the halls of William James, totally sleep deprived as everyone usually is, and looking for a thesis. And I ran into a lecture by Robert Stickgold, and he was doing stuff, looking at memory performance after a full night of sleep and showing that, well, you need at least six hours of sleep to show improvements in memory. And I thought, well, that's really interesting. I want to study something like that. And then when we started talking about it, I realized that, in fact, all those people who I knew who were nappers, I wasn't really a napper myself, but all those people who were nappers really swear by their naps. And it doesn't really jive with the nocturnal sleep literature. How is it that a nap of 20 minutes or an hour can make you feel really, really good when you need at least six hours to show any differences in performance? So that was why I started looking into napping as a thing to study. And while I was actually doing this research, I decided that I am, much like Kiki was saying, sort of guilty of this idea that I had this really bad thought that napping was for lazy people. And one day when I was falling asleep at my desk, I just decided to give it a try. And it was a great experience. I went into my friend Jay's office and I slept down on the couch. I just crashed out and I woke up an hour later. And I was able to work for the full till 2am without falling asleep. At all and feeling really great. And I thought, God, this is data works. It's really cool. So I started actually napping regularly in the lab. And then the entire lab actually started rotating on this couch. And we stole the couch from Jay and moved it into this kind of common area where we could turn off the lights and not have any disturbance. And then people all hours started sleeping on this couch just to let themselves get to a place where they could actually continue working and have much more stamina through the day. So that was pretty exciting to have kind of the first real nap positive workplace to go to and create. So I'm going to go over the stages of sleep. This is kind of just sleep 101 and I have a little pointer here. Let's see. So across the. Can you see here on this, I'll be on this one over here, the far one. So across the top over here you see this is the nighttime. So 11pm to 6am and what these colored bars represent are the different stages of sleep. And what happens is there's actually you go through a normal night of sleep. You'll go through about four or five what's called sleep cycles. And a sleep cycle means that you're going to pass through all the different stages of sleep. And I have them down here. Well, there's waking, of course, and then there's also stage one, stage, stage two, and slow wave sleep. And then once you wrap back up to stage one sleep, it turns it to be REM sleep, actually rapid eye movement sleep. Over here is the EEG output, which is just the electrical signaling that's going on in your brain during these different stages of sleep. And as you can see during waking, things are really busy. It's a very hectic stuff up there going on in your brain. Lots of brain areas are speaking all at the same time. And you're basically multitasking. And then once you fall into sleep, one of the biggest metabolic changes that you ever really experience happens every time you get to sleep. And everything really starts to slow down and quiet down. And you can see as you go from stage one into stage two, things start to slow down all the way into slow wave sleep. And this is what's called delta waves, which is basically your whole brain is speaking in synchrony at a very slow rate. And once you get through slow wave sleep, then you wrap back through stage two and you get up to REM sleep again. And REM sleep actually looks very similar to waking because it's a very busy time in your brain. But the only thing that's different about REM sleep from stage one is that you're actually paralyzed and you have these rapid eye movements. So what you might notice going across the evening up here on the top of the screen here is that there's a lot more slow wave sleep in the first part of the night. And then slow wave sleep starts to taper off and then you have an increase in REM sleep. So what happens is that you have a lot of slow wave sleep in the first part of the night and then you have slow wake tapering off and you have more and more rem. So each epoch is actually really different in terms of the distribution of the different sleep cycles. And what's interesting is that this doesn't really end when you wake up, it actually continues throughout the 24 hour cycle. And the nap wheel on the front of the book actually helps you illustrate this. And I'll get back to that a little bit later. But what this means is that naps in the morning are going to have more REM sleep and naps in the afternoon are going to have more slow wave sleep. And then finally the afternoon moves into the evening and then you have a lot of slow wave sleep in the evening. So keep all that in mind and we're going to move on. So let's get to the first study. What we did is just take a really simple visual task where people basically are just looking at a computer screen. I'm sure probably some of you did this in college and you had some visual stimulus pop up and you're just supposed to say what is the orientation of the line or what's the spatial orientation or whatever it was. And this was just oriented lines flashing up and you just say left or right. Now we're going to go real simple and just test them four times in one day and just first see what happens when we test them four times in one day. And then we're going to stick a nap in between the second and the third testing session. We have two naps. One is a half an hour nap and one is a 60 minute nap. But what we were really surprised to find was this is actually the no nap condition. So here is the sessions, four sessions in one day. And here is performance. And this is actually a different score. So people's initial score was their baseline and we subtracted the scores from there to see what was the change in performance. What we find is actually people's performance decreases across the day. And that has actually spawned a whole other area of research for me. But I'm not going to really go into that. But just so you know, the idea of being able to, oops, I hit this button by accident anyway, the idea of being able to continue working on the same thing all day long is just, you're just not going to be able to actually do it. So that's something to keep in mind. So now when we give people a nap right in between the second and third testing session, what we find is that performance actually levels out so that you stay at whatever level of deterioration you are at and you just don't get any worse, which is definitely good. But then when we actually add the 60 minute nap, people of course deteriorate in the second session and then their performance actually returns to baseline and it stays at baseline for the next two sessions. So we were pretty surprised to find that. So what's special about the 60 minute nap? Well, what you saw in the different cycles of sleep was that actually you go through slow wave sleep first and then you go through REM. So the first 60 minutes of sleep have a lot of slow wave sleep in them. And what we found actually when we compared the 60 minute nap to a baseline nap was that in fact they did have more slow wave sleep. So something about this slow wave sleep nap was helping you not deteriorate and stay at your optimal level of performance throughout the day. All right, well, the next thing we thought was what happens if we actually add REM sleep? Because REM sleep has been getting a lot of attention as being this really incredibly important stage of sleep for learning. So we thought, well, let's just extend the nap. We actually cut out the two middlemen. In here we just have one nap in the morning and one nap in the evening. And we have three different nap conditions. This time. One is a no nap control. The other one is a slow wave sleep only nap. So we stop the nap right around 60 minutes and we also have a slow wave sleep plus REM. So we let them sleep for the full 90 minutes because that's how long it takes to go through this whole sleep cycle. And then we test them again in the afternoon. So this is going to be a bar graph, but basically what I'm showing you here is this is the control group with no slow wave sleep and no rem. Here is going to be the slow wave sleep and no rem. And here's slow wave sleep and rem. So again, people, when they don't get a nap at all, they deteriorate even with just one second test session. And when you Give people only slow wave sleep. We had two naps. We had a 60 minute nap and a 90 minute nap. Actually. It doesn't matter how long you're napping for, but it's the fact that you have slow wave sleep in your nap that they don't show any deterioration. And then when we add the nap with slow wave sleep plus rem, what we find is that people actually show learning. And that's right, learning above baseline. So one thing that was really exciting about that is that this had been shown in nocturnal sleep. And so we thought, well, that's amazing, right? 60 minutes or 90 minutes of sleep is showing learning and you need at least six hours of sleep to show learning when nocturnal sleep. What's the deal? So we decided to compare this amount of learning to people who've actually had a full night of sleep and see how much, whether it's the same amount. So this is learning after a nap at 7pm and this is learning after a full night of sleep. So in fact, yeah, that napping was delivering the same amount of learning as a full night of sleep. So then we brought this nap group back the next day and tested them one more time in the morning just to see what would happen. Maybe that was, you know, they would saturate at their level of learning or maybe all sleep is additive and the more you do, the better you get. And that's actually what we found. So that this is the group, this is the nappers after a nap and a night of sleep and they're showing double the amount of learning. So that sleep does seem to be additive. No matter when you're getting it, you're going to get some benefits. So just to summarize really quickly is just we found that a nap with slow wave sleep can ameliorate this deterioration and that a nap containing both slow wave sleep and REM can improve visual memory to the same extent as a night of sleep. So one question that you're probably asking is how could that possibly be right? How can a nap of 60 minutes or 90 minutes actually give you that kind of performance changes? And one important thing is the time of day. And the way that I'm going to illustrate this is through this nap wheel. And just so I'm going to take this off the screen really quickly so you don't vomit. But oops. Oh, I keep pressing the wrong button here. Let's go back there. I just want to show you just how to look at this. This is the hours of the day. So this is midn and this is noon, right? And this is 6am and this is 6pm so that's the way to just orient yourself on this. So the interesting thing about sleep science is that we're continuing to find out new stuff. And what we keep finding is that different stages of sleep seem to be leading to different kinds of learning. So stage two slow wave sleep and REM each are offering you different improvements in your behavior. So stage two, we're just going to break this down. Stage two has been shown to be very good for alertness. So when you take a power nap, what that is, is the first 20 minutes of sleep is a power nap. And that's all stage two sleep. And that's why it really makes you feel really perky and feels like you're kind of, you know, back. You've got the reset button on. What it also does is it improves your motor memory. So anybody who does anybody here use a computer? Right. Okay. So typing anything that you're learning to play guitar, anything where you're actually using multiple kinds of motor movements, that's what you're doing when you're getting stage two sleep enhancing in that domain. So now let's look at slow wave sleep. So this circle basically represents how slow wave sleep is distributed across the day. And it, the way you can read it is the radius from the center will tell you basically how much slow wave sleep you're going to get. And it's very much determined by what time you wake up in the morning. And so in the afternoon you're seeing there's a lot more slow wave sleep. Afternoon and late evening, a lot more slow wave sleep than in the morning. So what we know about slow wave sleep is that it's deeply restorative. This is where you guys heard of cortisol and growth hormone. Cortisol is what basically is fight or flight. But it also gives you a lot of. It's a stress hormone, very good for you, but you don't want to have too much of it. And what happens when you get slow wave sleep is you have a decrease in cortisol and an increase in growth hormone, which is sort of the antidote to cortisol. So it's very restorative. People who do a lot of working out can usually want to take a deep slow wave sleep nap also clears the mind. So that deterioration I was showing you that slow wave sleep nap is going to help you not have that kind of ambush of too much information in your mind. It kind of clears the desktop. It also helps with declarative and spatial memory. And what that really means is say if you ever go to Google Maps and you're traveling around, you're trying to remember where different things are on the map, that's spatial memory. And then when you leave and you go talk to somebody, say I just looked at this, this and this and this. That's declarative memory, like really specific bits of information. So slow wave sleep is good for that. Then there's REM sleep. Now REM sleep is kind of the darling of sleep research. People get very excited over it and you know, it's probably for good reason. And what we find is that REM sleep doesn't really vary very much. It actually stays pretty sticks with a circadian cycle which doesn't really vary by your sleep habits. So you have a lot of REM sleep in the morning, as I told you about, and then it starts to taper off in the afternoon. And REM sleep has been shown to be very good for creativity, for gaining new kinds of insights for your perceptual skills. So any kind of thing where you're using your visual skills or your auditory skills, REM sleep is very good for and also dreaming. This is when you have most of your dreams. So in the morning when you have a lot of REM sleep is when you wake up and you think, I was just dreaming all night. It was actually just the morning area where you were kind of having a lot of those dreams. And nobody really knows what dreams are for. So I'll just say that I have no idea what dreams are for. And it's a very interesting topic but it's very difficult to study. And so thus far we're just sticking to learning and memory and hopefully sooner or later we'll figure it all out. So just putting it all together now, what we can find is actually that the way that this works basically is that you set your wake up time to be whatever it's going to be and then that is going to actually determine how much slow wave sleep you're going to have in your nap. REM sleep doesn't really change very much, as I said. So the important part is really where is the juncture between the REM and the slowest sleep? And that's that little cross right there. So usually for most of us who wake up between 6 and 8am it's going to be between 1 and 3pm and that's usually where we put most of our naps. That's where we feel that kind of trough in our energy. But if you're waking up, say at 4:00am, you'd feel it more between probably 12 and 2. And then if you're waking up at 10:00am, you'd feel it more between say, 3 and 5 or something. And this is this kind of stuff that you can start to play with because as I showed you, these different stages of sleep can really affect the kind of performance changes that you want to see in your life. And so you can kind of tailor your nap to actually suit your specific needs. And that's part of what we talk about in Take a Nap, Change youe Life. Okay, well, that's all kind of really fun and fancy and cool, but the truth is that not a lot of people actually do nap, right? And what most people do is, I guess I could just say, how many people here nap? Raise your hand. And how many people here drink caffeine? That's what most people do. So I decided to do a study looking at comparing napping to caffeine. And what we found. Well, first of all, about 90% of North Americans use caffeine and they drink really high amounts. Because in places like Starbucks, right now what we used to know is that a cup of coffee was like 100 milligrams, and now a cup of coffee is about 250 milligrams. So they're really bringing up the amount of caffeine. And that may have to do with the fact that it's an addictive substance. But anyway, so its cognitive benefits are mixed. That's the one thing that we do know, is that we're not really sure. We know it helps with alertness and it's really important if you're sleep deprived. But what is it doing for your brain in terms of thinking? So we just want to ask this question, how naps and caffeine compare on memory tests? So again, here's the experimental timeline. I have two lists of words. And this is going to be a verbal memory. So basically anything that you just were talking about with your friends. Can you just repeat back to me what it is that you just were talking about? So we have a list of words that they learn in the morning. One group takes a nap and it's. I think the mean minutes for the nap is like 65 minutes. There's two other groups and they get a pillow at 3 o' clock and it's an unmarked pill. So it could either be a placebo or it could be 200 milligrams of caffeine. And then in the afternoon they get retested on that Same list of words, and then they also just get tested on a new list of words. So what we're looking at is long term memory and short term memory, the ability to acquire new information. Okay, so what we found is kind of sad, is that naps, well, naps were good, right? They helped you improve your verbal memory. And this is in the seven hour delay. So the words that you remembered earlier this morning, you were better than. You were much better if you took a nap than if you took some caffeine. And this is a pretty significant difference here. But what we also found is that the things that you just heard, if you just had a dose of caffeine, you're probably also not as good as holding onto that information either. So. So caffeine was significantly worse than napping in this immediate recall, which was just his ability to acquire new information. So what does that mean in the real world? That means whatever morning phone call you had, you probably are not as good at remembering what it was than you would have been if you took a nap. And also whatever you just happened to talk to with somebody, maybe your boss or a client, that is also where you may actually have been getting a little bit of a deficit if you had caffeine rather than a nap. So to summarize, just the caffeine part is that caffeine is worse than napping for verbal. And I didn't show you this data, but also for a motor task, which is we were talking about the motor learning earlier and this is an interesting idea, right? Is that evidence that perceived benefits from caffeine are due to the elimination of withdrawal symptoms, but not actual cognitive enhancement. So it may actually be that we're becoming more and more addicted to caffeine. And so if we don't have it, we're going to not do as well on cognitive tasks. And if we do have it, you know, that's. We're just going to get to our good limit. And these people were actually not really big caffeine drinkers. That's another caveat of this study. So I'm going to end on. Yeah, Yeah, it wasn't always significant, but sometimes the placebo was better, sometimes the caffeine was just. It is different, but it's not significantly different. There's a lot of variants in the caffeine group. And I think that's another thing, is that some people do really well with caffeine and some people do really poorly. So the corporate nap initiative is something that I recently started in order to see how these laboratory results actually work in the real world. And what we're doing is basically trying to implement and assess napping as a tool for productivity in the corporate environment. So the first pilot program was at a Manhattan publishing house. We got 40 volunteers and over two month period they basically just said that they would do this on one month they would nap every day, and on another month they wouldn't. And we counterbalanced that so there wasn't really an order effect of like suddenly you were able to nap and you felt much better. And we did daily assessments. First when they got in, in the morning, they would just say, well, how did they sleep that night? And then when they left that day, they just told me, how did they do that day? Basically, were they more productive that day or less productive? So the first question that we really wanted to know is whether the naps would actually decrease their nocturnal sleep. Because I think a lot of people have that fear that if they start napping that they won't be able to sleep at night. So the exciting thing is, just one thing is that we made sure that they kept the same bedtime and wake time. So there was absolutely no difference in their bedtime and wake time. It's more that what was the quality of their sleep during that time that they were in bed and what was. So these, this is the graphs are going to be all looking like this. So just get used to this, which is that this is Monday through Friday and then this is the average difference. And this is the month in pink is the month where they were actually napping, and in blue is the month that they were not napping. So this is within subjects design, right? And what we find here is that people, when they are napping, they take less time to fall asleep, and when they are napping, they more often will sleep through the night. And that is a change in 14% and 12%. So we were actually really surprised to find that because I guess I was pessimistic and thinking we might actually mess up their sleep. But in fact, if you think about it, if you know any children who don't get their nap, they're actually more hyperactive and they have a hard time sleeping at night when they're not napping regularly. And what this may actually be talking about speaking to is that when you're actually answering this natural call of your biological rhythm, which is a dip in the afternoon, you might actually be more ready to sleep in the evening as well. Because what we also found is that for total sleep time at night, people were actually in the Nap. When they were napping that month, they slept longer. And they were actually reporting that they were more refreshed when they woke up in the morning. And that's about 20 minutes more sleep and also about a 5% feeling of being more refreshed. So now, of course, the question is, how do they do at work? And what we found is that of course, their daytime sleepiness decreased. So what we see here, but what's really exciting is that they actually reported that there was almost a 40% decrease in the amount of interference that sleepiness gave them at work. And what that means is that it's not necessarily when you're most alert that we're really concerned. It's more when you're really tired, the errors that you're making. So if we can find a 40% decrease on just a subjective measure, that that probably means that there really was an effect in enhancing their productivity. And just some questions on mood and quality of interactions. People reported they had a higher mood during the month that they were napping. The quality of your interactions, these were also improved by 11 and 10%. Alertness was also increased during the month of their napping and also stamina. So that basically means that that last half of a day after you've napped, you probably are able to go for longer and be more awake through that period. And that's also by 11% difference mental abilities, the thinking physical health has also improved. Okay, so just to summarize, so does napping interfere with nighttime sleep? No, on the contrary, people kept the same bedtime and wake time, but had more restorative sleep on the month that they were napping regularly. And are people less sleepy at work when they nap? Yes. Napping also decreased interference from sleepiness on the daytime activities by almost 40%. And lastly, how has performance improved with a nap? Well, on average, the napping made a 10% improvement in this highly stressed Manhattan workforce. So I'm just going to close now with just some last thoughts for people who are necessarily who may feel that napping is not for them. I will just say that napping is definitely a trainable skill. A lot of the reasons why we feel like we shouldn't be napping is because we maybe feel guilty about it or we feel like it's just not part of our schedule or that we're drinking like 20 ounces of coffee in the middle of the day. And what we should try to do is just decrease the amount of coffee that you drink and really just try to find a quiet place. And every day just give yourself 20 minutes just to lie down and give it a try. And not necessarily be too married to the idea that you actually have to fall asleep, but just that you're allowing your body to answer this kind of call of being a little bit in a low energy place. Also get to know your best sleep schedule and the nap wheel will definitely help with that. Just to figure out, well, when did I wake up? And then what's that perfect time of day that I should actually be napping and of course nap proudly. And here's the acknowledgments of just people that I've worked with in the past and very influential and helped me very much with all the research I've done and thank you. Are we going to do on mics or.

I sort of hear you saying take a 20 minute nap or take a 60 minute nap or take a 90 minute nap. So which are you saying?

Right? It really depends on what you can do and what you need to do. So a lot of the time when people are working in the corporate world, I don't actually think that you necessarily will need to take like a full hour nap because you know, for a lot of the time it's just getting you through that period of low energy. And so a 20 minute nap would be perfect and ideal. And and I actually always think that the longer naps are people who are doing a lot of like students probably who have more time but also are doing a lot of information processing, who are doing a lot of memorization, who really need their brains to be kind of working. And the people who need to work until 2am that's another issue. So people in the day to day, I think 20 minutes is perfect, but people actually, for this environment it might actually be better for people to be allowed to nap for say an hour because I hear that you guys actually have some late hours that you pull every now and again. So that would actually be more helpful.

I have the mic. Sorry. Sometimes I lay down to take a nap and I just can't. Like it's the middle of the day and I'm just, my brain is going. I was wondering if you had any advice for that or if you know that even if laying down, if you can't get to sleep helps.

Yeah. So a lot of the time when I actually bring people into the sleep lab, they'll say that they don't nap and that they'll claim that even after I've done EEG with them and I can see that they have nap that they say I Haven't slept. So there are some stages of sleep. Stage one and sometimes in stage two where you feel that you're actually really awake but that you really have passed through some place of you've shifted consciousness and you are actually in a sleep state state. But you may be able to hear things around you and you may feel like you're tracking your thoughts. But that state of relaxation can be actually very rejuvenating. So I would go for it anyway and not necessarily be too married to the idea of wanting to really pass out. It can actually just be a place of just low energy and quiet. That is very helpful.

If I work a 10 hour day and I take an hour nap.

Does.

It come out of wash with the 10% improvement in performance? And it seems like I'm losing 10% of my day to napping. But then if it's 10% improvement, I mean, isn't it just a wash and I might as well just work?

That's right. Yeah, that's a really good question. It's just the economics of this. Does it really work in terms of, you know, I would say that you're already entering into the day with a 4% loss. Right? That's what the Department of Labor has found. So you're walking in there. So when you take a nap, you're not only getting rid of the 4% loss, but you're also adding 10%. So then you're at 14% increase. Right. So yeah, there's going to be, you know, some trade offs. But if you look at all the other ways in which you probably would have to redo all the work that you're doing while you're really, really tired. There's also this other level of saving time, being more efficient getting it done the first time as opposed to, you know, dragging through and saying like, what was I doing yesterday? I can't believe I wrote that. Right. So I think there's definitely a trade off in terms of it's not the most efficient thing. You're right. But maybe it actually is in terms of that you're going to get your job done better.

Hi. So I was wondering, this is based off of a full night sleep and then a nap in the middle of the day. But do you have any thoughts on the Uberman sleep schedule?

Yeah, very, very interesting schedule, basically is that there's a whole group of people in the world that only nap and they're called Ubermen. But actually it's very, very difficult to do Ubermen and a lot of people do what's called Everyman, and that's that you actually have a chunk, of course, sleep of four hours in the middle of the night, and then you just nap for two or three times in the middle of the day. And, you know, I think if it's something that works for you, I think it's cool to experiment with. But a lot of the time, what you read on the blogs of people who do it is that they get sick really often. They also are very lonely. They don't really have friends because nobody wants to hang out with somebody who has to suddenly fall asleep in the middle of a conversation. And. And it's a hard life to continually manage. So I think that if we were living, if Google was the kind of environment where literally people were only napping, it would work. I think there's a lot of social constraints to the way that we sleep and the way that we're awake. So I think that social constraints could really help an Uberman kind of society. But unfortunately, that's not the way things work. What about people with sleep apnea?

Would napping increase their risk of heart attacks or whatever else it is?

You know, since I don't really do clinical work, but I do obviously work with people who do clinical work, sleep apnea is a really hard thing to talk about because you don't really know. Should they be napping more, should they be napping less? There's clearly, you know, there's sudden bouts of sleep that occur. I don't really know what to say about sleep apnea, honestly. And it's a. I think that no matter what, people with sleep apnea need to get treated. They need to get the CPAP because it'll improve their lives enormously and that all the naps that they take will be much more rejuvenating naps rather than naps that make them more tired.

I guess. I have two related questions. One is, how can I make myself less groggy when I wake up from a nap? And maybe that's because I have sleep apnea that I find that. And also, is there such a thing as too long of a nap? If I were to stay out late one night and wanted to try and catch up on that rest, would it be counterproductive at some point to sleep for two or three hours in the afternoon?

Yeah. Okay, so for the first question, a lot of people actually have problems with sleep inertia, and that's a really big reason why they don't nap is because they feel really groggy when they wake up. And so It's a really simple solution. You just don't sleep very long. You sleep up to 20 minutes and no longer. Because what, what sleep inertia is, is basically waking up in that heavy, heavy slow wave sleep. And so your brain is at that delta place and it's not able to kind of suddenly be up and multitasking. And it takes you about half an hour to an hour to really get out of there. So the best thing you can do is just start with like the 10 minute, 15 minute nap and just really lay down for only that amount of time and have something you got to do so that you just got to get up and get out of there. And you'll find it actually will take, it will totally get rid of the sleep inertia issue. And the second question is that past one full cycle of sleep, which is around 90 minutes, you really are not going to get any more benefits in terms of napping. Because I can point you to studies that show actually that sleeping two hours and three hours doesn't really do anything more for you. That one 90 minute cycle is actually all you'll need because you passed through all the sleep stages. So I don't really Recommend sleeping past 90 minutes and I also don't recommend sleeping around 3 hours closer to your bedtime. So in that there's a window there that actually can interfere with your nocturnal sleep. So you also want to be careful of that. Have you seen any studies in which rather than the no nappers continuing to work, they say play volleyball instead of napping? Yeah, it's an excellent study. And I definitely, I'm looking into meditation as one alternative break. And of course the next thing would be definitely to look at exercise because really interesting research going on in animal research is showing that exercise can really be boosting memory performance and lots of different kinds of performance. Obviously animal research in rats is very, very different than humans, I mean, supposedly. But this is. So we have to really test all these issues and we haven't. This is kind of a new field, but that's definitely on the list. Yeah, I had a question regarding Sue. I find when I try to fall asleep, it takes me longer to fall asleep and at the same time when I try to wake up, it also takes me like half an hour to an hour to actually wake up as well. And so for me. Are you talking about for nocturnal sleep or are you talking about daytime sleep? Yeah, nocturnal sleep. So then I find like for naps, I don't know, like naps that are short don't really Work for me because like the half an hour I'm supposed to be napping, I'm trying to fall asleep and I don't end up falling asleep. So I'm just wondering what the benefits of napping would be for somebody who may not be able to fall asleep, like right away. Yeah, so it's almost the same answer as the other gentleman. But. But I will say that there are probably states of relaxation that you get to that are very healthy and just allow yourself to take a break and to get to a place where you're lying down and you got your eyes covered. So light can very much inhibit sleep. So you want to cover your eyes. And especially for you, I'd even wear earplugs just to really create a situation where if you're having trouble getting to sleep, then make it so that your sleep health that you're really healthy in terms of making sure that you're getting all the things that you need. Basically it's called sleep hygiene. And so use the same thing for your nocturnal sleep as you would for your daytime sleep. And if you need to then wake up and you're afraid you won't hear your phone, put it on vibrate and put it under your back or under your pillow or something like that and continue to keep trying. Because I think actually your naps, if you can successfully nap, you actually might learn to successfully sleep at night as well. Both related, there are gadgets out there that are supposed to wake you up in the best phase of your sleep cycle so that you wake up less groggy in the morning. Are you familiar with those and how effective they are with respect to naps as well? Yeah, so none of those have actually ever been really tested and a lot of the claims that are made are without any scientific merit whatsoever. So it's really important to know that there's nothing out there that actually can do what those things say they can do. What they can do is they can track your activity levels, but it's not really doing PSG polysomnography, data collection. So it's basically tracking how active you are and when you're definitely you can see some things during what's called actigraphy, but you can't really do stages of sleep. So I'm very. I think we should be dubious about a lot of the claims that are made in like the airline magazines on the Internet. A lot of the things that people say is if they give them to me and I can test them, then I might believe them. But until now I'm A little. I think that a lot of claims are made that they can't quite support.

I have two related, maybe related questions. One, your diagram showing REM sleep happening later almost seems to say that jobs require creativity, like say programming. Actually people sleeping in is a good thing. So standard programmers hours might be a natural reaction. And so the related question is how do I figure out how much sleep I do need?

Right. Well, what's interesting about. Can I answer the second question first, which is I'm always really surprised by how difficult it is to actually find out how much sleep you do need. Because if we're all really sleep deprived and we feel great, then we don't really know what it feels like to be not sleep deprived. And so usually when you actually ask people to sleep longer, they feel even better, but they didn't really know before that period that they were going to feel even better. So it's a very difficult thing to actually figure out how much sleep you actually need. The average is around eight is what they say. They say sleep science says eight hours is the right amount of time. It used to be 10 hours. People used to sleep 10 hours and they had very different sleep schedules than we have now. So it's a hard one to answer. What was the first part of the question? Sorry? Oh, about the. Oh yeah, about the rem, exactly. Yeah, yeah. I think that definitely there's people who have found natural sleep cycles for themselves that really work with their own brains. You know how their brains work and definitely REM sleep. You know, the trouble with society is that we have school times and work times that really go against what some of our optimal sleep schedules are. And so there's, especially when kids, they have what's called a circadian phase advance, meaning that they actually need that they're naturally needing to go to sleep later and wake up later. But school times start to start earlier and earlier and earlier. So you see kids sleeping through most of their early morning classes. And so this is actually a real problem is trying to figure out how to make a society that actually is conscious of sleep need. And so when you're a programmer, luckily you're probably a pretty eccentric person in general and so you can kind of make your own hours. And I think that's usually a good thing, but it's not, you know, that's a special kind of job. And I think a lot of people who probably need REM sleep are not getting it. Long answer.

One fear I have of napping is of missing a regular nap. So my wife is at Home with our two boys and most days gets a nap in about an hour or so. But when she doesn't get a nap in, she's like irritable and you know, like she's just not better. Better off for it. And so it's almost kind of backfiring. The napping, is that something that you found?

Yeah, definitely. You get used to napping and so when you don't get to nap, I. Yeah, I have the same experience myself that now that I nap every day, if I don't nap, I sort of feel like, ugh, you know, like I didn't get my nap in. And you know, it becomes part of your life in the same way that if you don't have coffee in the morning, you also feel like you get a headache. So definitely we are creatures of habit and we definitely become used to whatever it is that we're telling ourselves to get used to. And sleep during the day is one of those things.

Is it better not to have a routine?

No, it's the most healthy thing to have a routine. Routines like our bodies, we have a circadian rhythm that is endogenous, that is part of our natural. We can't do anything about it. If we don't answer that, then there's nothing worse than a job that keeps you on a rotating shift schedule. So you cannot have a routine so that you work some nights and you work some days. Those people get terrible immune system. They're much more unhappy, they get into many more accidents. So definitely routine is good. And so answering that routine, it might be a little bit of a drag to sometimes have to do without it, but I think overall it pays.

Another experimental sleep life cycle that's popular on the Internet is the 28 hour day. I wonder if you have any opinions or knowledge about that.

I don't know about the 28 hour day. I know that when people are allowed to sleep, you know, at their own schedule. Right. So that not necessarily own schedule, but. Well, yeah, but also outside of the realm of light. And they don't know what time it is. They don't. They're just told to. They're basically in a bunker and they're just told to eat and sleep when they want. The day does turn into a 25 hour day, but I wasn't aware of the 28 hour day. I also know that submarine, I think it's an 18 hour day where they. I don't know why, but this is a really horrible thing that they do with people in submarines, is that they keep them on an 18 hour day. And so it's only like once every few weeks that you're actually on your natural rhythm and most of the time you feel completely out of it. So it's really. I don't know about the 28, but it's very funny to start mixing with these kind of schedules because you see how much creatures habit we actually are.

So I have no problems falling asleep at night. I mean I'm at like a light around 11 o' clock or so. But the problem I do have is night waking. So how do you suggest we compensate for that? Do we try to make up for those hours early in the morning and wake up a little bit later than I normally would or do I sort of just wake up the same time I normally would and take a longer nap in the afternoon?

The second actually. Yeah, so. So night waking is a really interesting thing because a lot of people, because sleep is now kind of moving into this idea of we should treat sleep and that there's lots of pharmacology to treat sleep. A lot of what may be a natural rhythm for somebody actually gets medicalized. And I'm not saying that there aren't real problems, but I also think that when you wake up in the middle of the night, get up and do something and then go back to sleep when you fall asleep naturally and then know that if you nap in the middle of the day, you're going to be making up for it. And I mean, I don't think that we should just ignore the fact that we may be staying up too long in the middle of the night. But I do think that there's a really interesting book that came out. I think it's called what we do at Night but by Richard Eckhart or something like that. But sorry, I'll get you the data, the information later. But he wrote a book, he's a historian and he wrote a book about the night and how people throughout history have actually use the night. And interestingly enough, people used to have what's called first sleep and second sleep. And in the middle of the night they would get up for like an hour or two hours and they would like, they would write about this in diaries, what they did in the middle of their night. And then they would clean the house and they'd go and hang out with the neighbors and it was just, it was a social occasion and then they'd go back to sleep and then they would definitely nap in the middle of the day. So some of these things where there's a night Awakening, I often think, well, maybe that's just you, you know, being in your natural rhythm. So. And then if you, if you know, well, I'm gonna be napping in the day, so I'll make up for it, you know, Then it also might take the pressure off and the worry off. Sometimes on like especially Fridays and Saturday nights, I'm up extremely late at night and then I'll find I'll sleep for like 10 hours and then like at 5 o' clock just crash again. Like does it kind of 5 o' clock in the evening? Yeah, like it just seems like on the weekends I absolutely crash and I'm asleep more than I'm awake. Is that kind of my body catching up? Yeah, yeah, definitely. So. And that's really not the best way to do it, so. Because, so one thing that people, it's totally typical to do is that we sleep on the weekends and we try to make up for all the sleep that we're lacking. But what's happening is when you're depriving yourself of sleep across a long period of time is it's not only that you're increasing what's called your sleep debt, but you also have increases in insulin levels that are not healthy, that you also have increases in cortisol levels that are not healthy. And so you don't give your body a natural rhythm to be active and relaxed. Active and relaxed, which is very restorative. And that is, you know, even though you probably can make up a lot of the sleep, you're not necessarily doing your other parts of your body very good. So I would, I always try to, you know, get people to sleep more on the week and then you'll actually have more kind of regular sleep and not change your sleep schedule by that much. So there should be like a one to two hour window where you really stay in that through the whole week. So you're saying that you stay up only till two in the morning on the weekend? Oh, yeah. Well then you are sleep depriving yourself though then on the weekend. And so then you need to make up for that sleep. So if you can, you know, it's hard because then what are you going to do on Saturday night? You obviously want to go out, right? But so it's a really hard thing to decide. Maybe you don't go out that much or maybe you go home at. I don't, I mean that's, it's. I can't tell you what to do. I find it really hard. But the sort of sleep doctor in me Says you shouldn't have a very large window between your nighttime sleep during the week and your weekend night sleep bedtime.

So I'm. These days I'm kind of on a schedule for all intents and purposes. I have two jobs. I have a job in the evening. And so my day is kind of planned down to the hour. And so in order for me to try to work in a nap during the day, it would mean getting less sleep at night. So is there. But would that be more beneficial to me and make me more productive in the evening or should I really be focusing on getting, you know, seven to eight hours at night skipping?

You know, I completely agree that it's really hard to find time in the middle of the day, but I bet you if I was with you in the middle of your day that I could find a time where you could just get little naps. Like, who was it, Martha Stewart? Yeah, she apparently, you know, I mean, this woman's a busy lady, right? But she naps in these little segments across the whole day. She'll like right in between meetings, if she has like 15 minutes, she'll just say like, don't bother me and she'll take a little nap. So what I do sometimes is I'll go to my next meeting and if I have to drive there or whatever, I'll just arrive like 10 minutes early and put the seat down and just take a little nap in my car just to kind of give me that extra edge and that extra amount of energy that I need. So I think that you're not going to probably find a whole hour, but you might find little chunks of 15 minutes. I had a question about, you know, how you said there's an optimal time for a nap. Is there optimal time for nighttime sleep too? Like, does sleeping from 10 to 6 versus 2 to 10 make any difference on your sleep? Yeah, definitely. So if you don't get, you'll actually will probably have a really hard time getting your slow wave sleep. If you don't get to sleep by around 11 or midnight because you actually lose a lot of your opportunity. Because what happens is REM comes in and you kind of. And you don't get enough of your slow wave sleep. It's the same thing. If you're waking up around 5am you're not getting enough REM sleep. And that's not to say that there aren't people who have different sleep schedules. I mean, there are some people who really literally can sleep for five hours and they're called short sleepers. And they do really well with having kind of really much less sleep than the rest of us. But if you are missing out on some of your sleep, but you'll give yourself the opportunity to try to sleep a more regular cycle and then see whether that is an improvement. I mean, all of this is all kind of self analysis, right? So if you are questioning maybe I shouldn't be sleeping, going to sleep at 2am, then start going to sleep at 11 and just see whether you actually feel more refreshed. She actually asked the question I want to ask already, so I'll pass the mic on.

I just wanted to ask her question again with another assumption. Assume that you're not going to be able to optimize her day or anything like that. Just the basic question of you have an hour you can cut out of nap time or an hour of nap time you can trade off for an hour of nocturnal sleep.

What do you do? I would actually nap in the day. What did you think I was going to say. Some days it seems like I need an alarm to wake up, but some days when I want to do something I like, I just jump up from my bed. Is there anything to do with. Yeah, yeah. We're not the same person every single day. You're right. Yeah. And sometimes it has to do with the weather, sometimes it has to do with our energy level, sometimes it has to do with just the fact that we're just happy one day and we feel really sluggish the next day. So I think that that, you know, it's hard to say that that all comes down to whether you slept well that night. But I think it probably has some kind of, you know, influence. And I think that there's many different things that kind of influence. Whether we've woken up and we feel like we want to attack the day or whether we feel like we just want to go back to bed. But sometimes actually when I feel really like sluggish, I'll just sleep a little bit longer because it may actually be that I've woken up in a kind of a dip in my sleep cycle where I'm actually in slow wave sleep. So I'll try to stay in bed a little bit longer and then try to catch a lighter stage of sleep, like stage two or REM and see whether, you know, whether that is influencing how I feel about the day.

I was wondering if you have any recommendations for other books. I've tried researching sleep online and I've been really disappointed. I can't really find anything accessible enough.

What kind of what do you mean by accessible enough?

I can find sometimes a lot of science, like really technical papers, or on the other hand, I'll find websites. Just tell me, like, go to bed at the same time every night. Don't eat right before bed.

Like, stuff that I already know. Just the same old stuff that you've already heard. Yeah. I will say that sleep is a pretty young field in terms of science. And so there isn't, you know, there's. It almost gets a little boring and tedious when you keep seeing the same list of sleep hygiene tips and stuff like that. And I think that with time there'll be more and more things. But I have a great book for you.

Okay.

That's all I can say.

I have a question about the different stages of sleep. And it sounded like there's just sort of variation from person to person, whether, like, how quickly you advance from one stage to another and what, like the architecture of your sleep cycle is. And some seem to be better than others. Right. Like, some are more restorative if you can get to your REM faster.

Right.

So is there anything that you can do that can change that or influence that?

It's kind of. Actually, same answer is that there is a list of kind of sleep hygiene. And like, some of the top things are that you want to. Like something that actually helps people not sleep very well is sleeping with a TV on or sleep like with a TV on in the same room. Because it kind of keeps you up and it keeps you in this kind of like half sleep state. And it's not very. It's not really restorative. So really, when you're purposely going to go take a nap or go to sleep, really make that what you're going to be doing and be kind of, you know, dedicated to that. Also, if you have. If you're light sensitive, wear an eye mask. If you're sensitive to sound, wear earplugs. So those are some definite things that will help you kind of focus on getting out of consciousness. But then there's also just keeping a real schedule because as I said, we were creatures of habit. Right. So becoming really like, okay, now I'm just gonna. Right, right. The second that you feel like you want to take a nap or the second that you feel. Feel like you really want to go to sleep, just go to sleep and then wake up when you feel like you're ready. And I think that those are the basics that I could recommend. So is the amount of sleep that you need seasonal? Does it vary? I mean, do you need more sleep in the winter than you do in the summer. It seems like that that's true. Yeah. Yeah. I can't really think of any studies that have looked at it, but I'm sure that there are some studies that look at it. Definitely when you go to extreme situations, like up in the northern Scandinavian countries, Iceland in particular, you really find a huge drop off in sleep in the middle of the summer and that there is absolutely no deficit that is concomitant with that. So it definitely is that there, you know, for some extreme cases, it may actually be that there's a genetic variation that allows people who have for centuries been in that area to actually be able to do without less to do with less sleep. And that you know, that in climates where it's a more kind of temperate zone and people are kind of in a more stable environment, they don't have such big swings. But definitely in those areas you definitely see changes to sleep that don't really change your performance levels. And they're supposed to be the happiest people, so they've done something right. So, I don't know, you said about the television.

I'm wondering if it's good or bad.

To sleep hearing music.

Yeah, I don't recommend it at all because it's, you know. But I think that that's also personal preference because I feel that, you know, if you keep yourself at some kind of level of awareness, it's very difficult to really block, get into a state of unconsciousness. And that's the goal really, when you're trying to get to sleep. So if you always have something that's kind of just a little bit there, it's actually becomes more of a very light form of just meditation almost because you're still able to kind of hear what's going on. So I don't recommend it. Not that I don't recommend meditation.

So if you could design a regular sleep schedule for office workers, what would it be? Just a default.

Yeah, so. Well, the default would definitely be that you go to sleep at 11, you wake up at like, you know, 7, and that you take right around 1 or 2. You take like an hour nap. That would be the best.

We have these little sleeping pods just outside here, and they're called Metro naps. I don't know if you've seen them, but what's your opinion of those? Are they effective?

Well, I guess there's a lot you could say about it, but basically you need a floor in your most primitive form of napping. And then you could also have your Rolls Royce right to nap in. So of all the nap kind of paraphernalia that is obviously the Rolls Royce kind of napping facility. And it's not necessary for everybody and not necessary that everybody has to kind of have a. I sleep on my floor, so it doesn't really fit in my office. So it would be kind of one of those things where if it does fit, fit and it's what you want, then that's great. And it's amazing and wonderful that Google provides them, then I would say use them. And also some people like to sleep on their side or flat. And so there's all these different ways in which, if that works for you, do it. Any more questions?

When you talked about sleep lag coming out kind of slowly out of sleep, I have a different experience, which is I wake up and I feel real grouchy. Is that related to the same thing?

Yeah, it's the same kind of thing. It's just a different manifestation. Yeah, yeah. So in that way, I would say either, you know, sleep a little bit longer or sleep much shorter. You know, you can basically time your nap around the slow wave sleep so that you're sleeping 20 minutes and making sure that you only have stage two or sleep an hour, because by an hour you'll definitely be getting into light sleep.

Better than something you would take.

Yeah. I mean, in general, yeah. But for me, I sleep 45 minutes and I feel great. So it really depends on the personal preference and where you are in the time of the day. Because if you're sleeping for 60 minutes in the afternoon, you're definitely going to hit slow wave sleep 45 minutes in the afternoon, you're definitely going to hit slow wave sleep. And if you're sensitive to slow wave sleep, then you're going to feel groggy. But if you sleep 45 minutes in the morning, you're less likely to hit slow wave sleep because you just don't have that much. What's called sleep production pressure.

Looks like I get the honor of the last question. So on the weekends, when I know I'm not going to be on my regular sleep cycle, like I'm going to go out with some friends and I'm going to be up until 2:00 in the morning, I do what we always called in college the disco nap. So I go home from work and I sleep for an hour or so and then I get up and get ready and go out. Do you think preventative napping is better than trying to catch up your sleep after you've deprived yourself of sleep.

Definitely. Definitely. It's. So there's three official names. One is preventative. Is it preventative? Yeah, I think it's preventative napping. The other one is operational napping. Which one is the prophylactic napping? That was the one that I thought was funny. I don't remember. But anyway, so there's basically nap before you're going to be tired, nap during your work or nap after. And what studies have shown which are the best is either to nap before or nap in the middle. And the worst thing you can do is nap after because by that time you've already probably gotten to a car accident or whatever it is. That's the long nap. Yeah.

Well, thank you very much for joining us today. And if anybody would like to have their book signed, please stay after and do so.

Thank you very much. Really fun.