Later School Start Time Cuts Teens' Car ...( A little more sleep means sharper you...),Health

A little more sleep means sharper young drivers, study suggests

MONDAY, Dec. 15 (HealthDay News) -- Letting teens sleep a little more by starting the school day a bit later may lower their odds for car crash injury or death, a new study finds.

The researchers found a 16.5 percent drop in auto accident rates for teen drivers when local high schools moved the start of classes from 7:30 a.m. to 8:30 a.m.

The possible reason? More sleep, more alert driving, the researchers said.

After puberty, adolescents are biologically programmed to stay up about an hour later each night, explained Fred Danner, the University of Kentucky psychologist who co-authored the study. This shift in their biological clocks then conflicts with having to get up earlier to go to high school than they did when they were in middle school, he added.

"It's as if they are operating on West Coast time in an East Coast world," Danner said. People blame teenagers' sleep deprivation on computers and staying up late to e-mail friends, he added. "But there is evidence they get phase-shifted by at least an hour. So you've got biology pushing you later and then you've got the school systems starting an hour earlier. By the end of the week, [kids] are a wreck and our study shows they might actually be in one."

In the study, the researchers surveyed around 10,000 Kentucky students from grades 6 through 12 on their sleep habits and daytime functioning, including auto mishaps. The surveys were completed twice -- first in 1998, when school started at 7:30 a.m., and then again in 1999, when the start time had been moved to 8:30 a.m.

Besides the 16.5 percent drop in car crashes, the researchers also found that the number of students who got at least eight hours of sleep per night rose from 35.7 percent in 1998 to 50 percent after the later school time came into effect.

The study appears in the Dec. 15 issue of
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