Is Your Teen a Night Owl? Blame Brainwaves

Oct. 31, 2005 -- Sleep scientists may have figured out why teens stay up longer than younger kids.

The reason may surprise you. It's not about watching late-night TV, surfing the Internet in the wee hours, or studying, working, or partying until dawn.

Instead, think biology -- brain biology.

In a recent sleep study, teens were slower to show "sleep pressure" in their brainwaves than younger kids. Sleep pressure is one of the body's go-to-sleep signals.

The slowdown in sleep pressure might be a natural part of growing up, write the researchers.

They included Oskar Jenni, MD, of the psychiatry and human behavior department at Brown University's medical school.

Sleepless for 36 Hours

Jenni's study included seven kids on the cusp of puberty and six older, more physically mature teens.

None of the kids or teens had sleep problems. They were healthy and well-rested before checking into a sleep research lab at Bradley Hospital in Providence, R.I., for the study.

The lab wasn't new to them. They had all slept there before for other studies.

This time, they were kept awake for 36 hours straight. Each got their own dimly lit room, where they were comfortably seated in bed. The researchers kept them company around the clock.

Every two hours, participants got a small meal and rated their sleepiness. Caffeine and drugs were out of the question.

Before and after the 36-hour sleepless stretch, they got a normal night's sleep at the lab. They had also had 10 confirmed hours of nightly sleep for 10 days before the study.

Old Enough to Stay Up Late

The teens' brainwaves were slower to show sleep pressure, the researchers write.

Shifts in teens' internal "body clocks" are probably also important, they add.

There are plenty of cultural reasons why American teens might stay up late. But the trend also shows up in other societies, note Jenni and colleagues.

Becoming able to handle long periods of wakefulness might prepare teens for adult responsibilities, they write.