Sleep and Human Performance
There are Differences Among People in the Duration of Sleep Needed
Transcript of Videotaped Presentation (http://www.bioedonline.org/presentations/)
Now, everyone needs sleep but there are differences among people in the duration of their sleep need. The real challenging question, in addition to asking what is sleep for, is the question of how much sleep do people need. Studies indicate that adolescents, and by that I mean in the age range from 13 to 21 years of age, as defined by the national Institutes of Health, generally need more sleep per day, something like eight and a half to 10 hours, than do most adults, who are typically in the range of seven to eight hours. Now, this is a problem because the way we currently operate our school systems, the older you are, that is, the closer you are to being in high school, the earlier school start time is. And many adolescents will stay up late at night. The bottom line is they’ll end up getting six, or five, or seven hours of sleep when they really need eight and a half to 10. And as you’ll see in a little bit, that produces a cumulative sleep debt. Adolescents are vulnerable to sleep loss in part because in modern society there are plenty of things one can do at night. In older agrarian economies and societies, people could go to sleep when it got dark, when the animals tended to go to sleep, because there wasn’t television and radio and computers and video games and telephones and a hundred ways to interact socially or to work or play. But now we have societies where millions of people are awake at night doing night shift work or traveling across time zones. Among the young adult and adolescent community, that also means work and play. The net result is that night time has become a much more active period. Midnight, after all, used to mean in the middle of the night. And now it means the time many people go to bed, or they even go to bed after midnight.
Excessive daytime sleepiness results when an adolescent or young adult—or anyone—doesn’t get adequate sleep at night. It often reflects what we call a sleep debt, which is indicative of inadequate sleep duration at night. It also can mean that you’ve got ample sleep duration but you have a sleep disorder that’s disturbing the quality or depth of your sleep. But for most healthy people, it’s simply a curtailment of total sleep time and they’re not getting adequate amounts of sleep. We know that this happens because we see, for example, young adults or adolescents or older adults who shorten their sleep during the work week and then on the weekends grossly over sleep by 10 or 12 hours because there’s this enormous physiologic pressure in the brain to catch up on the sleep that’s been deprived.
Now, as I mentioned earlier, you can also have poor sleep, as can adolescents, due to a sleep disorder. And this slide shows us three common disorders that can occur in adolescents. The first is, this bottom point, the delayed sleep phase syndrome. This is a problem that some adolescents and adults get into in which by staying awake until three or four in the morning, they suddenly discover they can’t fall asleep before that even when they go to bed early, like at midnight. The net result is they’re not only unable to fall sleep until three or four in the morning, they can’t get up and out of bed to go to school or anything else until nine or ten or eleven in the morning. They’re on a delayed sleep phase. The source of this problem appears to be in their circadian or biological clock, the 24-hour clock in the brain. The repair of this problem is complicated and requires medical attention to try to realign the biological clock with clock time in the social world. But it can be treated in sleep disorder centers. Another common problem is a difficulty falling asleep or staying asleep, widely known as insomnia. Many adolescents and young adults, experience stress or are light sleepers, or just have trouble being able to sustain sleep even though they may have a sleep debt and are very, very tired. And again, this could be treated by consulting a physician, particularly an expert in sleep and sleep disorders. And then finally some adolescents and children, we now know, can have something called obstructive sleep apnea, which we used to think primarily affected older adults. Obstructive sleep apnea refers to the cessation of normal breathing during sleep. The airway collapses once the brain goes to sleep. It doesn’t collapse when you’re awake or when you lie down, it only happens when you fall asleep. The net result is sleep is fragmented, you don’t sleep deeply and the next day you can be pathologically sleepy. All three of these categories of problems can occur in young adults and adolescents as well as some other even more unusual but rarer sleep disorders. They’re all treatable, but they can lead to sleep debt and problems functioning.
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Funded by the following grant(s)
This work was supported by National Space Biomedical Research Institute through NASA cooperative agreement NCC 9-58.