[Introduction by Jennifer Gibson]
Okay, so now that we can all wake up and listen to this one…. I just want to welcome everyone. We’ve been very fortunate at this ASCA clinic to have a group of professionals, mainly doctors, that have come in from the University of Miami and in doing so, working around their own schedules. It was mentioned to me that a lot of them are on rotating schedules, so, really, kind of finding out their schedules at last minute and coming up here to spend their time and share their expertise. And I think this is the first clinic where we have really had talks that pertain, actually to the coaches so I think that is a real nice addition to the clinic. This afternoon I think this is real interesting to have as a speaker, her name is Dr. Shafazand and she is from the University of Miami. She is a professor there, besides working in the pulmonary and critical care and sleep issues. So welcome….
[Dr. Shafazand starts]
Well, thank you for this opportunity. And I look forward to, actually after this talk, to answer people’s questions as well. This is going to be really an overview of sleep issues and how it pertains to the athlete; and, of course, how it pertains to all of us—not just the athlete. But the athlete would be the prime example, because this is what we are here to talk about.
I am going to briefly talk about:
what we do when we sleep,
why is it that we sleep—although I do not think that I can answer that question in all accuracy, but I’ll tell you some of the things that happen during our sleep.
sleep deprivation and the small number of studies that pertain to the athlete,
about what happens to them when they are sleep deprived,
touch on circadian rhythm issues, and mainly as it pertains to performance and to jet lag—which, if you have competition across several time zones, that is going to have an impact on your athlete—and finally
a topic that is near and dear to my heart: sleep disordered breathing; which actually affects all of us. So I think as coaches you need to be aware for yourself, and it will also affect your young athletes, and also your older athletes.
So it is going to be, as I said, a whirlwind approach to sleep medicine, but that’s okay. If there are other questions at the end, I am more than happy to answer them.
When we talk about normal sleep, we divide it into three distinct stages of consciousness:
 Awake—which is self-explanatory
and then the stages of sleep are:
 non-REM, versus
Non-REM sleep is progressively deeper and deeper stages of sleep. We divide it [non-REM sleep] into Stage I (all the way) to Stage IV. And REM is called the dream stage of sleep. So most of our dreaming occurs in REM sleep, but there are some other things that are occurring in REM sleep—the Rapid Eye Movement sleep.
[What we do when we sleep]
About 80% of our sleep time is spent in non-REM, so that is Stages I-IV; and 20-25% is in REM. We cycle through the night: from non-REM into REM and back again. This cycle takes about 90 minutes. So we have, if you were a normal sleeper and you got the recommended 7-8 hours of sleep, you would have about 4-6 cycles of [going from] non-REM to REM. But, of course, we are going to talk about what happens when you interrupt this cycling, and that is a form of sleep deprivation.
[Why do we sleep]
So, why do we sleep? Other than, of course, you feel rested after a good night’s sleep. No one really knows the exact answer. Why is it that we need eight hours of sleep? Why can’t we get by with two hours of sleep? In fact, if you looked across all mammals, one way or the other they are sleeping. So it seems to be something physiological; it is something that our body needs.
We do know that sleep, and lack of sleep, profoundly affects cognitive performance. So it is not a good idea to cram the day before or the night before an exam, and hope that you are going to perform well on your examination. We all do it, but it is not a good idea. It also has impacts our hormonal [levels]… there are a lot of hormonal influences that happen during sleep. It has effects on:
growth. So if you are dealing with young adults and adolescents who are your athletes, and they are still in the growing phase, sleep and the lack-of-sleep will have a profound effect on their growth.
the immune function
cardiopulmonary function. You will see towards the end of this talk—when I talk about sleep disorder breathing—that it really has a significant impact on cardiopulmonary function, and
a lot of metabolic activities: how we can use glycogen and glucose, how efficient we are, and then leading to diseases like diabetes–which I will talk about very briefly.
From the performance point of view, which I will highlight: REM sleep, we know [that] during that dream stage, somehow, memories are being consolidated. And that is not just the pleasant memories of what happened to you throughout the day, but whatever you learned. So, any cognitions, and cognitive association with the learning process, is being consolidated during REM sleep. And during non-REM sleep—particularly Stage II sleep—is when motor skills (the learning of the motor skills) get solidified. So, you can practice all you want, but if you deprive the person of sleep entirely, whatever they practice is not going to settle in. It is not going to be that automatic reflex that you would want as a coach; that as soon as they are in the water, they are doing it. You do not think about it anymore, you just do the right stroke. Right? That kind of learning process is occurring during sleep. It is not something that can be taught. Practice makes perfect, but my motto right now, what I want to get across, is that sleeping is necessary to achieve that perfection.
So, as a general rule, if we were to deprive someone of 24 hours of sleep, and then asked them to do some basic mathematical problems, like simple addition or multiplication, that should be automatic—you shouldn’t need to think about it. The people who are sleep deprived have problems solving these simple mathematical problems, and their ability to solve simple mathematical problems diminishes by about 20%. In fact, if you are sleep deprived for over 24 hours, it is the equivalent of having an illegal blood-alcohol level in terms of how you perform on these cogitative tasks. So that tells you first the importance of having a good night’s sleep and second not being sleep deprived.
Now, none of us on a regular basis are going to be up 24 hours and not have any sleep. But what we tend to do—and what becomes relevant in the next two slides you will see—is the chronic sleep debt that we incur during a lifetime. So, although we sleep at night; instead of sleeping the recommended 7-8 hours (for most adults)—and then for adolescents 10-11 hours—instead of sleeping that amount, we sleep 6 hours [or] 5 hours. We wake up early in the morning—because of practice schedules, because of lifestyle factors, etc.—and all of that is going to, over time, cause a sleep debt. It is this sleep debt that I refer to when I talk about sleep depravation, like the studies that they have been doing.
[What happens when you are sleep deprived]
So, as you see the picture of this little boy crying. Any of us have been there, where/when you are experiencing sleep debt, and you are tired, and you haven’t had a good night’s sleep. You feel grumpy. You are bad tempered or short tempered. You do not pay attention to things. We, ourselves, experience that and you usually forget about that experience; but, in fact, what we have shown—in various studies—is that:
There is an impairment in behavioral function—neurobehavioral function.
There is a reduction in growth hormone—and growth hormone plays a big role in repair of injured tissue.
There is an increase in energy expenditure. In other words: we are not efficient users of whatever energy stores that we have. We seem to have to burn up more, to compensate for the fact that we have had this lack of sleep.
There is reduced wound healing.
There is impaired motor function.
All of these are going to add up over time, when you think of the athlete and their performance.
So, in terms of the implications of this kind of chronic sleep dept or sleep depravation for the athlete, the bottom line is: because of this concept, we now know that during Stage II sleep is when you learn motor processes. Stage II and REM sleep, both of them, tend to be concentrated mostly in the early-morning hours. So we are talking from like 2:00 to 5:00 a.m. is when you are really spending most of your time in Stage II and in REM. So if you interrupt that sleep—during the 2:00-5:00 or 2:00-6:00 a.m. time period—you are, in effect, not allowing the person to learn whatever they were supposed to learn.
Experience has shown—and again, these have been through studies, small studies, but still, at least they are there—that if you learn a new activity and you—you know, I am obviously not a swimming expert—but if you learn a new stroke or a new movement in the pool on Day 1, that night, it is best for the athlete to actually sleep through the entire night and wake-up at a reasonable hour (like 7:00 or 8:00 in the morning). [This,] rather than interrupting the sleep and getting them to go back into the pool again at 4:00 in the morning the next day. The reason is because they have learned a new motor skill, and it will take that first night of sleep to consolidate that motor skill for the athlete. If you interrupt their sleep the second night, that is fine. It is really that first night that is the key. The second night you can, again, interrupt their sleep, they can go back into the pool to practice. The third and fourth night, they also need good sleep. So this has sort of been done in the form of performance tests for athletes, and they have shown, really, that it is the first night after learning a new skill, [and] the third and the fourth night, that are key in trying to consolidate that new skill into the memory so it becomes automatic.
[Question]: Is there a significance to the 2:00-5:00 time range, or is there a significance to the last three hours of their being asleep?
[Answer]: Ordinarily, sleep should occur at night, rather than during the day. So the sleep that you have, the naptime that you experience during the day—say you are sleep deprived and you need a nap—does not tend to go into REM. And does not have huge number/percentage of Stage II. It is really having a solid interval without interruption for sleep, and towards the latter half of that interval/night—which would be between 2:00-5:00 or 6:00 in the morning—is when Stage II and REM predominate, and that is where the learning is taking place. So that is the key. So, if practice has to occur at 5:00 in the morning, or more 4:00 in the morning [for waking up], then at least if they have just learned something new, let that first night be a comfortable night of sleep, and go back into the pool the second day, basically. Do not interrupt that first night of learning.
The other factor is that, when you are sleep deprived with this chronic sleep deficit, studies have shown that there is impairment in your visual and auditory reaction time, which is very key for competition in swimming and most other athletic sports. So you are not as quick to jump into the pool when you hear the buzzer, kind of thing.
The other is that your glucose metabolism is not as efficient as it should be. We have seen that, if over a period of 7-10 days you are sleep deprived or you have limited sleep—again, remember, it is not that you haven’t slept at all: you have slept, but instead of sleeping 8 hours you have slept 4 hours or 5 hours. So that kind of sleep deprivation over 7-10 days will make you a very inefficient user of your glucose stores. Between 30-40% glucose metabolism has been impacted, and glucose is necessary to provide energy to the muscles. When you do not have it, your endurance is going to be effected. So this would be key for endurance type sport; rather than quick—you know, sprinting—kind of sports [which] may not be affected by this. But when you are talking about endurance performance it really becomes key.
The other factor, or the other hormone, that is effected is cortisol, and cortisol is a stress hormone. What will happen is [that] when you have sleep-deprived periods the body perceives this as a stress, and so the cortisol levels become much higher than normal. Increased cortisol level have been linked:
to memory impairment,
to insulin resistance—which is key to that whole glucose metabolism / use of glucose,
over time it can lead to diabetes, but not in the short time period, and
impaired tissue recovery in athletes.
So if you have high levels of cortisol, it is not good for repairing muscle injuries. And with low levels of growth hormone that they are experiencing—again, because of the fact that they are sleep deprived—that combination is going to make recovery from any form of injury a concern.
We talked about aerobic endurance being affected when you have sleep deprivation. Psychologically everyone knows that you experience it yourself. That if you are sleep deprived you just do not feel well; your mood tends to be on the low side. Even if you are an upbeat and happy person, you are not as upbeat and happy as you were before. So for the athlete, interestingly enough, when they do psychological testing after periods of sleep deprivation, they perceive themselves to be more tired and more incapable of doing things than they actually can do. So if you push them, they will do it—they are capable of finishing whatever task you set for them. But their perception is that they are too tired. So they get tired earlier than they should from a physiological point of view because of the perception problem that they have in their sleep deprivation.
I tried to pick out studies that were related to swimming—because of where I am giving this conference—but most of the studies are really in basketball, football, weightlifting. Very few studies are done in the swimming world; this is sort of the extent of what is out there. As you can see, the numbers are small. This particular study is an ongoing study at Stanford University. What they were doing is looking at men’s and women’s swimming teams, and, in fact, they didn’t deprive them of sleep—which is what most studies are doing: they deprive them [of sleep] for some period of time and see how people do. Here [in the Stanford study], they ask the athletes to do whatever it is that they do—their normal routine—for the first two weeks of the study. But the reality of their normal routine for a college student who is also a competitive athlete is that they are waking up at 4:00 in the morning to go to the swimming pool and do their practice. Then they have to go to classes, then in the afternoon they have practice, then they probably have to go to another class or do their homework, and then finally, at some really-late time at night while they are trying to finish their homework and their studies, they fall asleep around 12:00 or something like that. So, they are chronically sleep deprived. That is the reality for high school students who are competitive in their swimming or in any other sport. For the college student it gets worse because the study burden may be more.
So they said fine, for two weeks do whatever you want to do, and we will just measure what you do in terms of your swimming performance—during the practice runs that they had. Then they allowed these athletes, for 6-7 weeks, they had to have ten hours of sleep straight. So they got ten hours of sleep, all of a sudden; from going 4-5 hours to 10 hours of sleep. And then they checked their athletic performance and compared it. They found that those athletes that had the extra sleep:
They swam a 50m sprint 0.51 seconds faster.
They reacted 0.15 seconds quicker off the blocks.
They improved their turn time by 0.1 second.
And they increased kick strokes by 5 kicks.
In other words: they were much faster in every aspect that matters, when you talk about competitive swimming, than the time when they where normally sleeping or sleep deprived.
So that is only in five athletes; will it bear out in larger numbers? The study is ongoing and maybe it will. But it is something to think about when you are dealing at the competitive level of swimming or any other sport, that you really have to take sleep into consideration. And so, again, another of my little glitchy mottos: to be competitive, you need to sleep. That’s the bottom line. You can practice all you want, but you also need to sleep.
So also monitored in this particular study: their wellbeing—the psychological wellbeing of the athlete. Their mood was much more improved, their ratings of vigor was higher, and they had lower ratings of fatigue. So their perception had also improved, and we all know how psychology has an impact on how you are going to perform.
So I am going to move away from sleep deprivation because I also want to talk about two other aspects of sleep. One is the whole circadian rhythm that exists in our bodies, and timing is everything in life and we should listen to our biological clock. So, whatever we do, that biological clock is sitting right there with us; so ignoring it can make us run into problems.
When I talk about a circadian rhythm, it is a rhythm that repeats itself approximately every 24 hours—that is a circadian rhythm. Most human functions, whether at the cell level or at the behavioral level or physiological level, demonstrate this kind of a 24-hour rhythm. Sleeping is, in itself, associated with a light/dark cycle, but demonstrates an almost 24-hour, or really it is closer to a 25-hour, rhythm.
The circadian rhythm that we have now, we know where it is located: it is in the suprachiasmatic nucleus in the brain. There is something there that keeps on going, regardless of what else is going on in the environment. What happens in the environment, what happens with light and dark cycles, will impact it; and that is how you can manipulate the circadian rhythm. But, even if you didn’t have night and day, this rhythm would continue in the human body. It will slightly be off—it will tend towards 25 hours rather than 24 hours—but it will continue, and that makes it that internal clock. So things like hormone secretions—growth hormone secretion, the cortisol we talked about already, thyroid hormone, insulin, melatonin—all of these follow a 24-hour cycle. Cardiovascular events, like your blood pressure, follow a 24-hour cycle. The blood pressure tends to dip in the early morning hours—that is normal. If it doesn’t dip, over time you become someone who has hypertension and you do not have that normal variation or dip. Heart rate is variable, not only throughout sleep but throughout the day as well. Your body’s response, and the muscle response to these various hormones, also follows this 24-hour cycle. The immune system is important here as well—again, I didn’t really touch that much on it—but if you are sleep deprived, there is some suggestion that your immune system is also impacted and you may be more prone to infection and illnesses. Although, I guess in a healthy athlete you do not see it as often as you see the average person who otherwise does not have that athletic and exercise background.
So just as an example of looking at the 24-hour cycle: so you have here, from 6:00 a.m. to 6:00 a.m. the next day. The alertness, as you would anticipate, at 6:00 to about 8:00 or so in the morning, the alertness is at its lowest and then gradually as the day progresses, it peaks; and in fact in the later afternoon to early evening you are very alert. And most of us have experienced this ourselves: that you can be really tired and then all of a sudden you get that second wind, right? It is around 8:00 or 9:00 at night that something seems to kick in. You have that second wind and you can potentially push through to about eleven o’clock at night, even though had you listened to your biological clock, you should have slept at that seven- or eight o’clock because you were so tired.
The other things I am trying to show here is the (there we go, pointer) your cognitive performance also follows that same kind of pattern in terms of your alertness. Sleep latency is: how long does it take you to fall asleep. So clearly, when it is earlier-on in the morning, you are going to fall asleep pretty quickly. As the day progresses, and your level of alertness increases, you do not fall asleep as much. The body temperature fluctuates as well. A lot of people have spent time looking at this body-temperature variation and how it impacts our performance, and whether or not you can manipulate the body temperature and therefore affect performance. It really has not panned-out to anything practical, but we are just aware that all of these follow a 24-hour cycle.
So again, in the swimming world: is there a circadian rhythm in swimming performance? And there have been several studies now that suggest that in-fact there is. This particular study that I am quoting: its numbers are small, but this is probably one of the more elegant studies that has been done to try and control for all the other factors that impact performance and just really hone-in on the circadian rhythm. So, in this study, they looked at 25 highly-trained swimmers, and they studied them over 50-55 consecutive hours. What they did is they told them [the swimmers] to sleep for an hour in the darkness and two hours of wakefulness in dim light—so they would wake them up. So one hour sleep, two hours awake; one hour sleep, two hours awake. And they actually asked them to perform a 200m swim trial that was scheduled every 9 hours during this 55-hour-consecutive observation. So, it is not something that… I mean, you have to do it in a lab setting; and you are specifically looking at the circadian rhythm.
The bottom line, what they saw is, that there is, in fact, a circadian rhythm in your swimming performance. Specifically, swim performance was impaired between 2:00 a.m. to 8:00 a.m. in the morning: exactly the time that we are asking—or not me, but you are asking—your athletes to wake-up early in the morning to be in the pool to exercise and practice. So they are not at their best at that time [2:00-8:00 a.m.]. In fact, the peak performance, believe it or not, for this set of athletes—again numbers are small so I wouldn’t put this as hard-fast rule, you have to look at your individual athlete—but the peak performance was at 11:00 p.m. Okay? So, really late at night for these athletes. Probably because the sample were young adults, who tend to fall asleep much later than the average general population of over 40-50. The young adults tend to fall asleep around 12:00 or 1:00 or 2:00; so 11:00 p.m.—which would be late for me—is not going to be late for them necessarily. But, in effect, what they found is that that mid-afternoon to early-evening is probably the best time, the best performance, not just for swimming actually, because other studies have borne this out. For other performance measures as well, like the amount of power that your muscles can generate and your function and your alertness and all of that. That time period in the late afternoon to early evening seems to be the best. And most World Records, if you go back in time—you have no control over when the championship match is, but if you are lucky enough to have the match in that time period—most World Records are set in that time period. Again, it goes to the fact that performance is best; it is a circadian rhythm issue.
And the difference between their best performance to their worst performance was 5.8 seconds. That is a tremendous amount of time, I think, in most performances.
Yes? [Question] How did you get them to sleep for an hour and wake up for 2 hours? [Answer] Well, you have to keep… you ring a bell; you have to wake them up. This [the study’s set-up] is artificial; you are not going to have that in the real world. The only reason that they did that was because [in] the real world you have the impact of light shining in—environmental cues, social cues—that will in effect make you more alert or drowsy. They wanted to completely remove all of that, and just see the body’s natural patterns. So they actually tried to deprive the body of every other cue and see what the natural 24-hour cycle was. That is why they did this and even their waking up was in dim light. So they were not swimming in bright sunlight; you know, out in the pool outside. It was all in a controlled environment. Just to look at that fact.
Okay, so I am going to touch briefly on jet lag and that actually impacts all of us: it is not just the athlete, you know. I am going to talk about it in the context of the athlete, but it does impact all of us. This, in itself, is a lecture by itself. There are people who spend their time—because it is so important that we are a world population and we are constantly traveling back and forth and there are people who are firm believers in this principle and others who do not necessarily believe in it. So I will tell you what is out there in terms of recommendations for jet lag.
So we have all experienced it. It is in essence either a transient insomnia or excessive sleepiness because of rapid eastward or westward travel across multiple time zones—and the key is the multiple time zones. So what is happening is that our own intrinsic circadian rhythm stays at the home time zone, and we are now faced with environmental cues that tell us it is a different time wherever we arrive. So they are out-of-sync. Our internal circadian rhythm is out-of-sync with what is outside in the world that we have arrived into. People who travel westward tend to be phase advanced—I will explain to you in a second what that means. I will use as an example traveling across the U.S.
So, if you are on the East Coast and you go to the West Coast—pick a state like California. So you are in Virginia and you go to California: there is a 3-hour time difference, and California, in effect, is 3 hours behind us. So as a traveler, going from Virginia to California, if my bedtime is eight o’clock in Virginia; in effect it is six o’clock there, California time, when I have to go to bed. Lets make it more realistic – my bedtime is ten o’clock; it is really seven o’clock p.m.—7:00 p.m. California time. So when I am at 7:00 p.m. California time and my body says it is 10:00 p.m. bedtime for me here in Virginia, what will happen is that I am going to feel tired at 7:00 p.m., right? I want to sleep at 7:00 p.m. and so that is where the phase advancement comes. My tendency, compared to the locals, is that I want to sleep earlier. But what I will do is I am going to wake up earlier, much earlier in the morning than locals; because I wake up at Virginia/Eastern Coast time of around six o’clock, which is 3:00 a.m. for the Cal-Pacific time—California time. So, in other words, I have this problem of feeling very sleepy earlier on in the evening, when all by friends and colleagues are not sleepy, and then waking up at three-in-the-morning knowing: now, what to do with myself, right? So that is Westward travel.
And the opposite happens when you are traveling Eastward. So all of a sudden you have insomnia because your local time tells you that it is 6:00 p.m., everyone else’s time where you have arrived is 9:00 p.m. and they are getting ready for bed; and you are like, I don’t want to sleep at 6:00 p.m. Why should I sleep at 6 p.m.? So you have insomnia. But you have a difficult time waking up when it is morning for the East Coasters, because now it is also three- or four-in-the-morning for you and it is work time for them: six- or seven-in-the-morning for them. So that kind of thing we have experienced, and that is just a few time zones—that is really three time zone changes. If you go to Europe or you go to Australia or you go much further, what will happen is that now you have more than three time zone changes, so it becomes even more complicated.
When you go north-to-south, or obviously within the same time zone, you do not really experience jet lag. You may be tired because of the plane ride and all of that, but you do not really experience jet lag.
So the common symptoms are either insomnia and you have excessive daytime sleepiness. You are not as alert during the day. And then there is some non-specific GI problems, like you are usually constipated, you have decreased mood, and you just do not feel right and that happens to all of us—but some individuals are more susceptible than others.
So for the athlete that does this kind of traveling because of competitions in another country where there are time zone changes, the advice has always been—and you do that—is that you go earlier so that you have time to get accustomed to the local time, the local customs, so you do not have this experience of jet lag—which for sure is going to interfere with performance and, sort of, endurance, really. If you had the competition immediately, the next day [after] you arrived, you are going to be in trouble, actually.
So, westward travel as we talked about: the early evening sleepiness and increased wakefulness during the early morning hours. Eastward travel: difficulty falling asleep and difficulty waking up the next day.
Typically, we do not do anything about it, because if you have the luxury of time on your hands, then it does resolve by itself—you do not really have to do anything. The general rule of thumb is: one day for every time zone change. So it takes one day to finally get for every [time zone]… so if we are talking about three time zones, it will take three days before you get into the California custom if you are going from Virginia. If you go much further—you know, you have experienced it yourself—it may take up to a week, and then it is time to pack-up and go back again. So, you know, that is the problem: that we are so rapidly changing our schedules, we just do not give our bodies the time to naturally adjust.
So this becomes actually more difficult when you travel eastward, than if you travel westward. You can think back in your experiences. If you are going west, you adjust much faster than if you are going eastward; because insomnia seems to be a more difficult thing to tolerate for people. And then the waking up kind-of drowsy, because you have to wake up earlier than what you are used to, is just something that most people do not like.
So what can we do about it? Now, as I said, there is a whole science that is dedicated to this and I am just scrunching it all into one slide, okay? In general, what is recommended is: if you have to adjust quicker, what you need to do is get yourself exposed… first off, get yourself into that local time practice as soon as you can. Some people even advocate, if you have the luxury and your lifestyle permits it, to do it while you are at home. So you start adjusting your time and sleeping at the destination time’s time and waking-up at the destination time’s time, if you are at home. That is the luxury that most of us do not have, because we still continue on with our lives until we travel. So you cannot really, you know, go to bed at 6:00 at home: you have everything else going on in your life, so that may not be practical.
So then the other thing is, okay: how can I take advantage of the light and day cycle and what will that do? So if you are traveling for westward travels: you are going to California. Once you arrive in California, if you could get yourself exposure to bright light at the time of arrival, it does wonders for making your sleep time later, enabling you to sleep much later and, therefore closer, to local time’s custom for sleeping, okay? Conversely, if you are going eastward, you need to get yourself exposed to bright light the first thing in the morning. So you come to Virginia from California, and if you happen to arrive the first thing in the morning, it is best to spend at least 30 minutes to 1 hour in bright sunlight. And what that does is it is going to allow you to fall asleep much sooner than your set-time at home, and therefore you do not experience insomnia as much.
And that bright-light exposure is actually recommended, and that is an easy thing to do now. There are commercial light boxes that people who are constant travelers—and for whom being sharp and with-it immediately, as soon as, they set foot to the new destination is imperative—some of them actually invest in these light boxes that they take with themselves because you cannot guarantee that the sun is going to be out, right? So, these light boxes are certain wavelengths and you just spend 30 minutes staring indirectly at a light box, and that actually works because what it does is it entrains your circadian rhythm: it pushes it to where it should be for the new destination.
Now, some people have used melatonin. In fact, melatonin: probably the only place where there is some evidence that it might be effective, in terms of training your circadian rhythm, is in this whole jet-lag scenario. The problem with melatonin is you have to time it correctly. It has to be used at the right time, otherwise you are going to mess up the circadian rhythm, anyway. So I wouldn’t recommend doing it on your own. I think if it is something, that is if you are going to recommend for your athlete or for yourself, you have to really talk to someone who knows about it before you just start taking it on your own. However, as a general rule, you take the melatonin around 10:00 p.m.—so between 9:00-10:00 p.m. of your destination time, ok? So, if you are in the plane at that time—you have not reached your destination—you can take it at 9:00-10:00 p.m. of your destination time, and then sleep on the plane. If you are not going to sleep on the plane, then do not bother taking it, okay? But, once you arrive at your destination, that particular night if you take it around 9:00-10:00 p.m., it will help your circadian rhythm to entrain faster into the local customs, okay? So, that is the general rule of thumb. But, again, if it is something that you are going to do as a routine, for your team for example, then it really should be in consultation with someone who knows what they are talking about so that you don’t mess up the schedule.
For some people we have used short-acting hypnotics, you know. I would not recommend that in an athlete because first off you do not know what the impact is going to be on that particular individual. And then secondly, sort-of the residual effects on performance, especially if you have a big competition coming up the next day or two after travel, is not well studied/not known, and it is not really a good thing to get used to. Caffeine, again I do not tend to advocate caffeine. Of course, it is going to minimize your excessive sleepiness, but if you can time it so that you have the luxury of adjusting to that time zone naturally or through exposure to bright light, [that] is probably the best way to go rather than forcing the issue with medication.
[Sleep disordered breathing]
Okay, so I am now shifting to sleep disordered breathing. This is the last topic I am going to be talking about. The world of sleep medicine is big, but these are… I just wanted to highlight key points for everyone. The reason I picked sleep disorder breathing is, as you will see, it has a huge impact on your cardiac health. Your heart health, your lungs, your high blood pressure, and of course—you know—we can talk about performance for a second, but really this is more a topic for all of us, rather than just focusing-in on the athlete.
So what is sleep apnea or sleep disordered breathing? What that is, is this repetitive collapse of the upper airway (and I will show you diagrams). Upper airway is anywhere from the nose all the way down to the trachea—so all the way down to here, past the vocal chords. This repetitive collapse of the upper airway that occurs during sleep leads to these mini-arousals in the brain. So even if you have the luxury of nine hours of sleep, if in fact you have sleep disordered breathing, you have repetitive arousals—so your brain never gets a chance to get to those deeper, restoring stages of sleep. So you never get to the Stage III, IV; you are constantly being interrupted in your Stage II. You may never even get to the REM, or dream-stage, of sleep. That will have the effect of you waking up feeling that you have had a really bad night’s sleep. You may not even be aware that you were waking up, or having these mini-arousals, but you will wake-up feeling un-refreshed. Tired, still sleepy, wanting to continue to sleep.
And apnea means you completely stop breathing, and then we have another term called hypopnea where you actually have shallow breathing—so you do not breathe as much. What that does is the oxygen level in your body will dip—will go down with apnea or the hypopnea—and the heart rate will speed up, the blood pressure will shoot up, and all of these will have long-lasting effects.
This is a general statistic, and again as you will notice there is nothing for young adults or athletes, but in fact sleep apnea can happen in the pediatric population as well and you will see the risk factors. So when you think about yourselves or the students that you teach, you will see that some of them may have those risk factors. So it is not exclusive to the adult [population], but my statistics [presented here] is just talking about the adult.
As we age, we are more likely to have sleep apnea. The population prevalence seems to be about 4% in middle-aged men and 2% in middle-aged women—and middle-age becomes relative. In this particular study, middle-age is anywhere from 40-60, so that is considered the middle-age group. So as I said: it is all relative; as you get closer to 40, you no longer consider yourself middle-aged. The other thing is that, of course, if you look at the nursing home population—now we are talking people in their 70’s, 80’s, 90’s—all of a sudden this prevalence goes up. So, you think to yourself: so what, I am not there; this is not going to affect me. But, in fact, it will (and the risk factors are on the next side). But I just wanted to highlight the consequences of sleep apnea: why it is such an important condition to be aware of.
So it [apnea] has been associated in very nice, long-term, epidemiology studies with increased risks: for hypertension, for heart attacks, for strokes, for irregular heart rhythm. There is significant neurocognitive impairment with sleep apnea, because of the fact that you do not get a good quality sleep so you have: memory problems, learning problems, difficulty procession the information. And in fact, there may be an increased risk of death in patients with sleep apnea—compared to the general population. It has been also associated with diabetes.
For the rest of us who do not have sleep apnea, it is an important issue because people who do have sleep apnea tend to be more prone to car accidents. So if you are driving along any highway in the U.S., you would appreciate the fact that if the driver next to you falls asleep or is not paying attention, they are going to put your life at risk as well as their own. In fact they have shown in these studies that people who snore—which is one of the symptoms of sleep apnea, but not an entire symptoms—so people who snore, were three times more likely to have been involved in a car accident than people who do not snore. And then when they formally tested for sleep apnea, they found that people who were formerly diagnosed with sleep apnea were 7 times more likely to have been involved in multiple car accidents—now they could be fender benders to more severe car accidents; nevertheless, they are car accidents. So multiple car accidents in the five years that they studied, they were 7 times more likely than the average person who did not have sleep apnea. So it becomes a health/population issue, as well or a societal issue as well—not just that particular individual.
So just to talk about the components of the airway; this is where the risk factors come in. Anything that blocks any of these passages: the nose, nasopharynx, oropharynx, all the way down to the larynx. So anything that causes narrowing of any of these passages can predispose that person to sleep apnea. Now, the most important risk factor of course is obesity—which is becoming more and more common in our society. And obesity, since you know BMI is Body Mass Index, is considered 30 and above—is considered obese, right? Then of course you have morbidly obese, when we are hitting the 40’s.
So, especially upper airways, so neck circumference being large is going to be a risk factor, regardless of what else the rest of the body is doing. So if the fat distribution is a lot in the neck, it is going to be an interesting issue. Now, here comes a point—I do not know if you are going to ask me this question now, but I am going to answer it anyway, to the extent I know it. In the swimmer, the neck circumference tends to be big, not because they are obese but because the muscles get developed. The shoulder and neck muscles get predominantly developed. No one has done a study to say whether that truly is going to cause more sleep apnea in that particular population [i.e. swimmers]. This is an otherwise healthy population, especially the athletes are an otherwise healthy population. But it would be an interesting study to do because clearly the airway will be affected by the fact that now you have more muscle mass—not fat, but more muscle mass.
Now, the other factors are: male gender, more than women; but women once they hit menopause… Yes?
[Question]: If you loose the weight, will you decrease your chances [of getting/having sleep apnea]?
[Answer]: So if you already have been diagnosed with sleep apnea and you were overweight and you lose the weight, the severity of your sleep apnea may get better. Very rarely does it completely go away. So the weight is just one factor. It usually is in conjunction with several other risk factors as well.
But I do not want you to go away thinking weight and that is it: it is only the overweight people that have this condition. You can have a super-thin person, who can have craniofacial abnormalities, or sinus issues with chronic nasal congestion and a chronic mouth-breather, who can have sleep apnea. In the Asian population, for example, thin, young women—who clearly do not have an ounce of fat on their bodies, but because of their anatomical facial structures where the cheek bones are not as prominent as say the Caucasian population, and the nose bridge is not as prominent, it is flatter—those people are at risk for sleep apnea and it is not because they are overweight, okay? So, the thing is that craniofacial abnormality becomes very important.
If you look at the profile, someone who has a small jaw compared to the rest of their head: so they are narrow-faced, long-jaw kind of image. Or [someone] who has a jaw that is receding: it is small and is sort of set back, as opposed to it being on a straight line with the forehead. In reality, the jaw and the forehead have to be on a plane, if you look at profile. So, if that jaw is not in that plane, that means the face, and more importantly the upper airway, is more narrow than the average person. Someone who has a small head, who has a large tongue, in children and in adolescents [this] is tonsils. If they have large tonsils and adenoids, that blocks the airways, so that they can be predisposed to sleep apnea. And, of course, I mentioned the chronic sinus problems, so the nose is blocked: so one passage is gone. We are all naturally nose breathers—we should not be breathing through our mouths. So if someone predominantly breathes through their mouths, there is a problem here, and that problem here can also translate into sleep apnea as they sleep. And we talked about the large, thick neck.
Of course alcohol and any sedatives or hypnotics that someone takes is going to make the problem worse, because alcohol relaxes all the muscles. And when the muscles relax, and you already have a narrow airway to begin with and you are asleep—which is a natural relaxed state of muscles to begin with—the airway gets smaller and smaller and can completely collapse. So people—you may have noticed in your own experience—that if you consume alcohol, your bed partner may comment that you snored last night, right? Because, ordinarily, you may not snore, but when you really drink a lot of alcohol and you aggravate the problem more, it becomes more prominent.
So, what the person that has sleep apnea may complain about is snoring—or they actually do not complain about the snoring, it is the bed partner or the roommates who complains about snoring. And then they may say that when, as I said, when you wake up in the morning you feel sleepy, you feel tired, you feel fatigued. And this is assuming you have had enough time to sleep. So, sleep deprivation aside, if the person wakes-up and still feels tired—as if they have not had a good night’s sleep—you want to start wondering: is there something else that is driving this fatigue?
It is a physically restless sleep, because they have these mini-arousals. They can be tossing and turning a lot; they wake up with the bed sheets all scrunched up. If it is extreme enough, because of this rapid sympathetic surge, which is what happens when your airway collapses and you do not breathe, your blood pressure shoots up, your heart races; and what will happen is you can have night sweats. Everything is surge… as if you are preparing for a marathon or you are running a marathon—is what I liken it to, because you are constantly performing, even at nighttime. There may be in the extremes: personality changes, moodiness. And the reason is this person is chronically sleep deprived; it doesn’t matter how many hours they sleep, they are sleep deprived. And, of course, intellectual impairment. And then they wake up with morning headaches; again because through the night because the heart rate has shot up, the blood pressure has shot up, and that is going to have an impact on morning headaches.
Now, some famous people who may have sleep apnea. and of course you see the one in red because I thought it was relevant: I have not diagnosed him with sleep apnea, I do not know his medical history—Michael Phelps’ medical history. But his facial features are very much like someone who is thin who obviously is not overweight, but may have sleep apnea because his jaw and his chin are much smaller than what should be normal for his face, for his body form. So anatomically, without even looking/examining him close up, he appears to be at risk for sleep apnea. And I do not know if he snores or not. But other famous people like William Howard Taft, Napoleon, Winston
Churchill, Theodore Roosevelt, Queen Victoria: these are all people who have had key decision-makings in our… not in our lives but in history. And given all we know about sleep apnea and the potential impact it has on intellectual impairment, we can sometimes maybe question some of their decisions and excuse them because of a medical illness. But the reality is that it is just really their anatomy and their body habitus that puts them at risk. So, having said all of that, I do not want to go into the treatment of sleep apnea and all of that—that is really a topic in itself that I do not want to bore you with—but I just wanted to raise awareness of this.
And so in the athlete, while weight is not the issue—it is really their facial anatomy, and especially if you are dealing with adolescents and young children, what you will see is the tonsils and the adenoids play a big role and they can have sleep apnea. In children, they [researchers] do not talk about sleepiness or tiredness. They could, but what it is, is “hyperactivity”. So they act out because they are sleepy. The ADHD literature is considering sleep apnea as one of the risk factors, because it worsens their hyperactivity because of the sleep deprivation that they have.
So, in general, factors that affect sports performance as you know—you know better than me—there are many factors that go into sports performance. But what I really wanted to highlight is that there are the circadian rhythms, that we briefly talked about, and, of course if you are traveling and you have to be competitive, and this whole balance between time awake and sleep loss, the chronic sleep deprivation will have an effect on your athletes at the competitive level. If it is just… and of course lifestyle becomes important, you know. If you are considering the wellbeing of the human being who is performing a sports activity, for their wellbeing, they need enough sleep.
And so to sleep—per chance to dream—these are my final points for sleeping. For all of us, we should consider sleep as important. We spend at least a third of our lives asleep: there is a reason for it. We may not know it scientifically yet, but there is a reason for it. So, at least, resist the urge—and I have to remind us, for myself as well—resist the urge to cut on your sleep so that you can do every other-thing that we need to do in this life. So pay as much attention to sleep as you do to other aspects of your own health and your life. And specifically for the athlete who is preparing for a particular competition, allow that athlete, especially in the weeks—1-2 weeks—prior to that competition: allow them to catch up on their sleep debt. Allow them to sleep, because that is going to do wonders for their performance.
It really is trying to maintain regular sleep/wake cycles. So regular [time] to bed, “early to bed, early to rise…”—you know that expression: there was some wisdom in that. Regular times to go to bed, and regular wake-up times. Most of us tend to really have erratic sleep patterns during the week, and then try to make-up for it on a weekend. That is better than nothing, better than not making up for the sleep, but it is not the best way. So, if you have maintained that regular sleep/wake cycle, it is really important.
And if you have to have a nap—and that’s the thing: I do not usually advocate naps because I really want people to consolidate their night sleep as much as possible. But if you need to have a nap, the best time to have a nap tends to be around 1:00-2:30, and only for 30 minutes. If you go beyond 30 minutes for your nap, what you are doing now is getting into the deeper stages of sleep and you wake up from that very groggy and not as well-rested as you should be. So if you are hitting REM sleep in your nap, if you are actually having dreams while you are napping, that is a clue to you that you are sleep deprived. You really need to get more sleep and not make up for it in a nap. But a 30-minute power nap is okay, if you do it early in the afternoon between that 1:00/1:30/2:00/2:30 time zone—but not really beyond that. If you push it beyond that, you are decreasing your own drive to sleep at night; and then you are faced with insomnia when it comes to sleep at nighttime.
[Questions & Answers]
Okay, now I am open for any questions, if anyone has any questions. Go ahead….
[Question]: I have a 9-minute delay on my snooze button. And sometimes I feel like that 9-minutes is the deepest I sleep all night. Is that…
[Answer]: Well, what time do you wake up?
[Q]: Oh, anywhere between 4:00 and Noon. [laughter]
[A]: 4:00 and Noon: so you actually have a very erratic sleep habit, is that correct? Yes, okay. So, it is possible that if you feel that it is deep sleep, it is because you are so sleep deprived that you skipped the normal range of: Stage I, Stage II, Stage III, Stage IV, REM; and you go straight into Stage III REM, Stage III REM. Because you are so sleep deprived, you do not give yourself the time to sleep properly. So, for you, definitely try and fix your habits to a more regular sleep/wake cycle, if you can.
[Question]: I apologize for being late. I want to ask about, and you may have mentioned it before we came, but what about in Japan and the morning finals [2008 Olympics]. How does the circadian rhythms—in China rather [not Japan]—how will that impinge on their performance?
[Answer]: And that is actually a complicated question. So the competition is early morning hours? Is that correct?
[Q]: The finals are.
[A]: The finals are in the early morning; in Beijing. So, these are general rules. Clearly the timing of the finals is not in your control; there is nothing that you can do about that. So, because… especially for US athletes or any other athletes going to China, now the key becomes… they have had, they should have enough time to adjust their circadian rhythm to local-time circadian rhythm. The performance is going to be terrible if they arrive two nights before, and are expected to, you know, participate. So you really need, ideally if you can have a week or so because you are now traveling across 5 or 6 different time… actually six or more different time zones when you go to China. So you really need at least six days to get into Chinese time—to Beijing time. So that is where the only thing that you can manipulate is that and adjust exposure to the light—as we talked about, you know, exposure to light—early on so that you can adjust to the local time zone as much as possible. But you can do nothing about when the timing of the actual match is. In general, if you are lucky enough to have matches in the afternoon, though, all things being equal, afternoon matches are best for swimming. It seems that way, not just for swimming, for most athletic endeavors.
[Question]: How many of those 30-minute naps can you take a day?
[Answer]: No more than two. And remember it has to be early in the afternoon. If your nap is at 6:00- 6:30, you are interfering with your nighttime sleep. So if you can fit two naps between the time of 1:00-4:00 that is fine, but most people cannot do that.
[Q]: If they finish prelims early, take a nap and then get up to eat and go back and take another one before finals.
Yes, go ahead.
[Question]: Can you talk a little bit more about human growth hormone, sleep, mitochondrial function and just in general the body’s ability to adapt to a workload.
[Answer]: There are some more/deeper physiological studies than what I spent time on, but that is precisely what… I think…. The importance of sleep as it pertains to the athlete is the fact that you have the time for recovery. So when you have these periods of sleep debt and the growth hormone is decreased, it interferes with many cellular levels. It [HGH] is a hormone that is essential to body repair. So what is happening is that you now have a decreased growth hormone. You already have the injury set-in; the muscular injuries set-in at a cellular level because of the performance that you have put in, the training that you have put in. And then your growth hormone is down because you are sleep deprived. On the flip side, cortisol is high because it is a stress hormone, because you are sleep deprived. And that combination—not that healing will not occur, it will occur—but it relatively decreases the body’s ability to repair. It will still occur, so it is not an on-and-off phenomenon. It is all relative compared to individuals who have normal sleep, and they train. So that is why, you know, I put all these points out [in this talk]. But the reality is if you… what is important to you is that one particular person, as opposed to the averages that I am quoting. So that one particular person may or may not show all these manifestations that I am talking about. But definitely we have seen that, on average, the repair is impaired when you do not have sleep. And this is something that I did not go into too deeply because it is something that I have not spent that much time looking-up myself, but that whole over-training concept that I keep on reading in the sports literature that they are over-trained, over-trained: a lot of people think that the lack of sleep or the sleep debt is also somehow playing a role into that as well and into the repair processes.
Yes? Sorry. [Question]: Is there a way of getting this….
[Answer]: Oh this talk? Yeah I think they are taping it and someone just got a copy—Gary got a copy of it so it should be available in the yearbook or something that is coming out. So this is available, yeah.
All the way back, yes? I can barely hear you…
[Question]: With normal sleep, how much time should an athlete have from wake-up to optimal arousal?
[Answer]: But that is assuming they have had normal sleep to begin with right?
[A]: Because that will vary. It usually takes about half-an-hour to an hour for complete arousal, for the entire system to be on-the-go, so to speak. Now, it is variable, everyone is variable, and it really does depend on what happens the night before, but usually about an hour or so.
[Q]: Just to follow-up: would that be the same in the nap situation?
[A]: So the nap situation: that is why I am emphasizing 30 minutes. So if you sleep more than 30 minutes, it also probably will take an hour, but you will just feel groggy. And you have experienced it yourself: if you have the 1-2 hours sleep, you just wake up really feeling groggy. And the reason is that you are waking up from a deeper sleep. So you should not permit yourself to wake-up from either REM or deep sleep because that emphasizes the grogginess. But in the nap-in-general scenario, as well: for like a 30-minute nap, within 30 minutes you should be up and going at full speed again. It really shouldn’t impact that much.
[Question]: As a coach I very, very seldom have more than seven or eight hours between the end of the evening practice and the start of morning practice, especially during the summer time. Am I pretty much out of luck there, or is there a Plan B I can fall back on? Add this to the fact that on many occasions, I will be going 4-5 weeks for seven days a week because of competitions on the weekends.
[Answer]: Absolutely yeah. So you are talking about yourself or are you talking about your athletes?
[Q]: I am talking about myself.
[A]: You are talking about yourself, yeah. So it would be very glib of me to say ‘oh, change your lifestyle and sleep’ because I know the realities of every lifestyle. So the only thing I can tell you, for you, yourself, is that you have to, every 7-10 days at least—but ideally closer to 7 or 6 days—give yourself the opportunity to sleep a solid eight hours at night. For you in particular—again, I do not usually advocate this, but for you in particular—take advantage of those power naps, because you definitely have a sleep debt; there is no getting around it. So if you were to cut back on something that is not tremendously important, and sleep for the 30 minutes during the early afternoon, then I would say ‘go for it’ because that is the only opportunity you are going to have to sleep. And then every 6-7 days attempt to get two nights at least in-a-row of good solid eight hours of sleep, without the alarm clock, without the pressure of having to wake-up early in the morning. That is really the only way you can get around the situation, because your lifestyle and the reality of your work is dictating how much sleep you can get.
[Question]: What is the optimal time to get 8 hours of sleep?
[Answer]: So again, everyone is variable and as I say 7-8 hours of sleep is an average. What I would recommend for most people is probably around 10:00 or 11:00 at night, and usually you have a winding down period. So the best sleep hygiene is for you not to finish doing whatever you were doing on the computer or on TV or whatever at 10:00 and then expect to fall asleep like this. But rather to move into ‘I am going to get ready for bed’ phase—what we do for our children (read them bedtime stories, etc., you know). That is the winding down period. So even adults need a winding down, and then by eleven. To be able to sleep by 11:00 would be perfect. If you could do that and that would mean that if you want seven hours of sleep, you are getting up at six in the morning, right? But, if you have to get up at four in the morning because you are coaching at 4:00 a.m.; then if you translate out to sevens hours back, you are going to have to be in bed by 9:00 or 10:00. 9:00/9:30. So that is where the difficulty of the eight hours comes in.
Now, what is a good experiment for you to do? You are sort of roughly on vacation right now; I mean, even though you are attending [the 2009 World Clinic]. So if you had no time obligations whatsoever. Think of when you were on vacation. There was no alarm clock: you could go to bed whenever you wanted and wake up whenever you wanted. How many hours of sleep would you get that would make you feel wonderful about yourself? That is the key. That is the amount of time of sleep that you need as the individual. Because seven or eight hours is the average human need; but some people clearly are six hours, others are nine hours. So, think of yourself on vacation, without any obligations on your alarm clock. See when you go to bed and when you wake up naturally, and that is the amount of sleep that you need.
[Question:] What about falling asleep with the TV on or your iPod?
[Answer]: Absolutely forbidden: you really should not be doing that. But, you know, we do it, but you really should not be doing it. The reason you are falling asleep with the TV on is because you are tired, and you are pushing yourself; you are watching the TV and you eventually fall asleep. That is your body telling you that you really should have gone to bed earlier, rather than have the TV on, or your iPod, and you are falling asleep.
Now, do you use the iPod because you are relaxing? That is your relaxation mode: that is fine. Listening to relaxing music in dim light, especially if you are prone to having difficulty falling asleep, is a different story. But TV, computers, reading the newspaper, reading hard-core jarring stuff or hearing jarring stuff on the news: anything like that is not sleep inducive. Relaxing music, dim lights, believe-it-or-not [things] like chamomile tea, you know, if you have problems with insomnia: those are relaxing. A hot bath. For some people, exercise; not immediately before going to bed, but at least three or four hours before your bedtime. So if your bedtime is 10:00, exercise around 6:00 is very good, because what it does is the body temperature is affected and it really allows you to go into the sleep mode. But close to bedtime not a good idea to exercise, because you are at peak body temperature and that is going to prevent you from going to sleep. Okay?
Any other questions? Yes?
[Question]: I actually just got through reading an article about the temperature and light in [the location/room] where you are doing your primary sleeping. The optimal temperature being around 70-72°.
[Q]: What is the optimal….
[Answer]: That is correct. The light for sure, and even the temperature…. You do not want it to be too hot, because again, sympathetic nervous system gets primed when it is too hot, so you are not going to be able to sleep. And too cold: you are fighting off the too cold. So 70-72° F is actually optimal. Or for people who work in Celsius it is like 20° C, 19-20° C is optimal. And the dim light or no light at all is good as well. So, in reality, if you have to take your nap, if you need that power nap: 30 minutes. The best is going to be in a really dark room, and that is why a lot of people—you know—have the covers and all of that on their eyes. But a really dark and quiet room is the best place to sleep.
[Q]: Does that light effect you even if your eyes are closed?
[A]: Yes. The receptors do not need the eyes… the light receptors do not necessarily need the eyes to be open to perceive light. The brain does perceive light. So if even, you know, those of us who forget to, say, draw the window covers and tend to wake-up because the light shines through—and I mean, your eyes are closed and the light shines through. So you will have a perception of lights, so the dark room is really key.
[Question]: How does gastric motility affect going to sleep?
[Answer]: In what sense? I mean, obviously if you are hyper-motile, I mean, you have to go to the bathroom that is going to interfere with your sleep, but…. In terms of the eating you mean? Okay. It is interesting, the whole eating and the body’s focus on metabolizing and digesting the food and its impact on sleeping. There is a balance there, because if it is too heavy a meal; and really it is the contents of the meal and how much you have eaten that plays a role, so a high carbohydrate load is sleep inducive, okay? But a high protein load is not necessarily sleep inducive. So it depends on what your last meal is before you go to bed. And that is going to have an impact just because of the contents of the food and how much energy is metabolized during the process. In that sense, there is an impact on sleep. But in general, and this is not for its effect on sleep but more its effect on your overall health and weight gain, you are supposed to have at least a 3-hour time span between your last meal and your time to go to bed because you are obviously the most inactive during sleep—in terms of your basal metabolic rate. So a high meal, high carbohydrate contents/ any content meal right close to bedtime is going to… the energy is going to be available during your least active time. And over time, that is going to lead to obesity. So that is why it is sort of not recommended to not eat close to bedtime.
So okay. Thank you.