Most high school students are chronically tired. They juggle school, sports, homework, chores, friends and family.
To meet all these demands, surveys show, high school teenagers usually stay up close to midnight on school nights. And then they have to get up early the next morning, typically around 6 or 6:30 a.m., to get to school on time, as most high schools start classes around 7:30 a.m.
By Friday, most teens are very tired, says Dr. Helene Emsellem, a sleep researcher with George Washington University. And then comes the weekend.
"Every parent of a teenager knows that if you try to get them up in the morning on the weekends, they're tired, grouchy, irritable and not the charming individuals that they're capable of being, because they're so exhausted," says Emsellem, a neurologist who also runs the Center for Sleep and Wake Disorders in Chevy Chase, Maryland.
She says the typical high school senior gets less than seven hours of sleep on school nights. But they need a great deal more.
Growth Spurts Call For Sleep
"Most studies show a fairly consistent 91/4 hours' sleep requirement," says Emsellem. "So there's a huge gap between what they're getting on an average school night and what they require."
An adolescent's biology bears some of the blame for this sleep problem. As teens progress through puberty, unprecedented growth occurs in body and brain that requires lots of sleep.
In addition, there's something else changing: The very brain chemical that makes one feel sleepy — a hormone called melatonin — is released later and later in the evening as teens get older.
Because of this shift in the onset of melatonin, teenagers don't feel sleepy till later at night, says Stephanie Crowley, a sleep researcher at Rush University Medical Center.
"A 16- or 17-year-old might be able to stay awake later compared to a 10-year-old who will likely fall asleep on the couch watching TV," Crowley explains.
Accruing A 'Sleep Debt'
So when a teen's propensity to fall asleep later is coupled with the early-to-rise school start times, most high school students end up accruing a "sleep debt" of five to 10 hours by the end of a school week.
And teenagers' typical habits on the weekend create even more chaos in their sleep-wake cycle.
"What the majority of adolescents do is they will try to recover their sleep on the weekends," observes Crowley. "And what usually will happen is they'll stay up late to socialize with friends and then sleep-in in the morning."
But this sleep-wake pattern makes things worse for the teen, not better, adds Emsellem.
"So even if you catch-up by sleeping in late on your weekend mornings," she says, "by doing so, it makes it harder for you to fall asleep by 10 or 10:30 on Sunday night. And you start all over again, sleep restricted."
But Emsellem offers some suggestions for the weekends, based on her sleep research in the lab — and her personal experience of raising three daughters.
"As a parent myself, I feel like a criminal if I ask them to get up at 7:30 or 8 in the morning. But I do try to get them up by 9. And I encourage them to get some activity and some light exposure in the morning."
Let There Be Not Much Light At Night
Light, Emsellem says, is a "drug that promotes wakefulness" in the morning, in the same way that darkness can promote sleep at night. In the evening, she recommends dimming and even turning off some lights in the house to minimize light exposure.
The teen should also try to make the transition to sleep time by taking a warm shower or doing some gentle stretching. Emsellem suggests that there be a lights-out time in the teen's bedroom during the school week and that they try to stick with it.
But if the teenager gets into bed and turns out the lights but cannot sleep, Emsellem says that teens get just as frustrated as adults by just lying there in bed, doing nothing. In that case, electronics can be helpful if used carefully — for example, soothing music or an audio book. But she suggests limiting such sleep aids to 30 minutes.
Making The Case For Sleep
Emsellem wants teenagers to understand what sleep does for them every night.
"I think it's important for teens to recognize that during the day, they're gathering information," she says. "But they're really not learning it till they sleep on it."
Another tip for teens: no caffeine — including chocolate — after mid-afternoon. Emsellem says caffeine stays in teen's system for at least six hours.
Experts also recommend naps. Over the weekend, an hour or so can help a teen catch up on sleep. During the school week, naps should be short — 20 to 30 minutes — and are best taken during study hall or a break before mid-afternoon. Otherwise, they could interfere with nighttime sleep.
Naps can be particularly helpful when teens have a test in the afternoon. "Studies have shown they'll do better on their test with a nap midday," Emsellem says.
There's another advantage to an early afternoon nap: Teens will then have more energy and concentration to power through homework later in the evening. Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.