Dozing at Your Desk?

Cate Martin

Good news for snoozers: If you can't keep your eyes open in homeroom, it's probably not your fault. Teenagers actually need to go to bed later and wake up later, says Dr. Mary Carskadon, a sleep researcher at Brown University who has devoted much of her 25-year career to studying adolescent sleep.

Dr. Carskadon says that the body's "internal clock" changes during adolescence. Many high schools start too early—some as early as 7 a.m.—when teenage bodies are still programmed to be asleep, she says.

Most people think teens stay up late just to talk on the phone and watch late-night TV, and that's why they can't get up at the crack of dawn. But research points to other reasons for sleeping

in—reasons that might be more acceptable to your first-period teacher.

In a recent survey, Dr. Carskadon asked 400 adolescents questions about their sleeping habits, such as what bedtimes and waking times they would choose if they could, or how they would do in a 7 a.m. gym class. Then Dr. Carskadon measured the results of her survey against each student's stage of physical development. She found that the students who were farther along in puberty, the set of hormone -triggered changes teens undergo as they grow, were more likely to prefer staying up late and sleeping in. Therefore, there must be a biological basis for sleep patterns, Dr. Carskadon says.

In addition, Amy Wolfson, a professor at the College of the Holy Cross in Worcester, Massachusetts, asked 9th- and 10th-graders to try to fall asleep during the school day. She noted how long it took them to fall asleep. Keeping in mind that most people take between 15 and 20 minutes to fall asleep at the end of a long day, the results were astonishing. Ninth-graders took an average of 9.5 minutes to fall asleep. Tenth-graders took an average of 8.4 minutes. The sleepiest 9th-grader was out cold in 5.1 minutes, and the sleepiest 10th-grader was snoring in 1.8 minutes. What's happening here?

Remember when you were little and you jumped out of bed bright and early while your parents were still groggy? Clearly, people of different ages have different sleep patterns. Young children tend to wake up early and easily, while people their parents' age prefer to get up (and go to bed) later. It shouldn't be surprising, then, that as children enter adolescence, they naturally start staying up later too.

SLEEP, OVER THE YEARS

Throughout life, the pineal gland (located at the base of your brain) secretes a hormone called melatonin. One thing that melatonin controls is your daily rhythm of sleep and wakefulness—the cycle of how tired you feel first thing in the morning and how awake you feel at 1 a.m. Scientists believe that high levels of melatonin trigger drowsiness. Around the age of 6, your nighttime blood levels of melatonin are known to be highest. Then your nighttime levels begin a lifelong decrease, with a rapid decline at puberty. This sudden drop may be related to the teenage tendency to become night owls.

To make matters worse, many junior high schools start earlier than elementary schools. And high schools may start earlier than that—even though high school students are the least likely to be morning people.

This is because schools often share buses, with the high school route running as much as two hours earlier than the elementary school route. The older students usually get the early route because they have more after-school interests, like sports or the school newspaper. If their days started later, they wouldn't get home until dinnertime or later.

Dr. Carskadon thinks high schools should adjust their schedules to meet students' physical needs. For a school day that begins at 7 a.m., students have to be up at a deadly 5:30 or 6 a.m.

"When kids are sleepy, education becomes a one-way street," Dr. Carskadon says. "Teachers have to put all the energy into the system, and the kids don't."

So why not give teenagers a break and let them sleep in? Opponents of the idea say that school is preparation for the real world, and in the real world people have to be at work on time regardless of how they feel.

In response, Dr. Carskadon asks, "In the real world, how many people start lunch at 10:30 in the morning?"

EIGHT ESSENTIAL HOURS

If your school district won't change, what can you do? Dr. Carskadon says that teenagers should find a way to get at least eight hours of sleep a day. If it's not practical to go to bed at 9 a.m., an afternoon nap can make up for some lost hours. Sleep-deprived teenagers who finally get enough sleep for a whole week (not just a couple of days) will notice a difference, Dr. Carskadon says. They'll feel better in class, find studying easier, and be more alert and productive. "Sleep is not a luxury," she says. "It's a necessity."

Appendix: Sleep Cycles

The average night's sleep begins with a descent from wakefulness to drowsiness, light sleep, and finally deep sleep.

Scientists can identify and graph these stages by tracking the brain waves of a sleeping person. Throughout the night, this pattern of sleep stages reverses itself and then repeats several times.

At the end of each cycle, before you drift back into deeper sleep, you dream. Scientists call this stage REM sleep (for rapid eye movement) because your eyes move around rapidly when you dream.

As the night goes on, the dream stages become longer and the deeper-sleep stages become shorter. Toward morning, your dreams could last more than an hour, though you may not remember them.

Stage I/ Drowsiness: Body muscles start to relax. Your heartbeat slows and you drift off.

Stage II/ Light sleep: You may still be trying to find a comfortable sleep position.

Stage III/ Deep sleep: Your blood pressure crops and your muscles relax.

Stage IV/ Deepest sleep: Your body barely moves. Only a loud noise will wake you.

REM sleep: Though the rest of your body is relaxed, your brain and eyes are very active and you dream.

From Science World, March 8, 1996.