Sleep In? Dream On?

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Is waking up at the crack of dawn your daily nightmare? That's what a lot of teens used to think as they scrambled to get to high schools in Edina, Minnesota, by 7:25 a.m. No more! Since 1996, high schools there start at 8:30 a.m. — 65 minutes later. "One hour makes an unbelievable difference," says Gregor Feige, 17, a senior at Edina High School. "When you're not dead tired, you can go to school and actually feel alert." Edina made the switch after doctors cited evidence that teens are biologically programmed to stay up later — and snooze later — than children and adults.

"A change occurs in the biological clock of older adolescents," says Dr. Mark Mahowald, director of the Minnesota Regional Sleep Disorders Center in Minneapolis. "If they're in school at 7:30 a.m., chances are they're getting up earlier than their bodies tell them to."

High schools in Minneapolis followed suit last year by delaying the opening bell an hour to 8:40 a.m., and students report they feel more alert. Teachers are handing out higher grades, and disciplinary problems are down. Last June, Congresswoman Zoe Lofgren (D-California) drafted legislation that, if passed, would encourage U.S. high schools to hold the morning bell until at least 9 a.m. "It's time for high schools to synchronize their clocks with their students' body clocks, so they can achieve their full academic potential," Lofgren says. But before you fluff up your pillow for extra shut-eye, check out some sleep science:

Why do you need to sleep anyway?

Sleep allows organs and muscles to recuperate. Cells repair themselves. Connections among neurons (nerve cells) are strengthened. Meanwhile, the sleeper's brain processes and files all information collected throughout the day. All this clean-up work helps you feel refreshed after a good night's sleep.

What makes teens like to sleep late?

If mom or dad thinks you like to sleep in because you stay up too late watching TV, here's your defense: New research shows that teen sleep patterns may be beyond your control. Instead, they're dictated by circadian rhythm, the internal clock that regulates all organisms, from plants to humans. The circadian rhythm in humans triggers the pineal gland (located at the base of your brain) to discharge a surge of hormone called melatonin. Melatonin makes people drowsy as the evening winds down. The pineal gland slows its production of melatonin in early morning — just in time for you to wake up. Puberty (the teen growth stage when reproductive organs become mature) causes a circadian phase delay, or a shift of as much as two hours in the daily schedule of sleep and wakefulness, according to sleep expert Mary Carskadon of Brown University in Providence, Rhode Island. For three to five years after the onset of puberty, teenagers experience a kind of ongoing case of biological jet lag. Researchers still don't understand why.

Do teens need to sleep more than others?

After puberty strikes, teens need an average of 9.2 hours of sleep, or about an hour more than older and younger age groups. Infants, the biggest sleepers, need up to 18 hours of slumber every day.

What if you stocked up on caffeinated soda and pulled perpetual all-nighters?

That's what a 17-year-old San Diego student named Randy Gardner had in mind when, in 1964, he stayed awake for 264 hours (11 days), a record that won him a place in The Guinness Book of Records. After staving off sleep for a few days with cold showers and loud music, he could no longer focus his eyes and had to give up TV. His speech slurred, and he fell into a silent stupor. Sleep experts now believe that long sleepless stints like Randy's can be dangerous. An experiment conducted at the University of Chicago in 1983 showed that rats died when kept from sleeping for two and a half weeks. Message: Listen to your body, and sleep tight every night!

YOUR BODY CLOCK
Midnight to 8 a.m.: Your body is programmed to sleep. Graveyard-shift workers, like truck drivers, are error-prone because they're tired. Blood pressure, pulse, and body temperature reach their lowest levels before dawn.

8 a.m. to noon: Mental functions, like memory, are at their sharpest. This is the best time to study or concentrate in class.

2-6 p.m.: Body temperature hits its high point. Your sense of smell is at its best. It's the peak period for physical feats, like the 50-yard dash. By late afternoon, you're starting to drag as you reach the drowsiest part of the day.

6 p.m. to midnight: Your body secretes stomach acid to digest dinner. Asthma sufferers are most likely to have an attack as hormone levels drop.

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