As students progress through high school, demands on their time from hectic social activities, jobs, homework and family obligations increase and they sleep less to fit them in, as the study shows. Compounded with their delayed sleep-wake pattern, many students are getting up for school when their bodies tell them it is still the middle of the night.

National Sleep Foundation research shows that delaying school start-times by an hour or more increases the amount of sleep adolescents get and improves their performance in school. However, to promote optimal sleep, Eaton said that adolescents should have set bedtimes before 10 p.m. on school nights and consistent wake-sleep times every night.

Brandy Roane, an expert in adolescent sleep patterns at the Munroe-Meyer Institute of Genetics and Rehabilitation of the University of Nebraska Medical Center, said, "Given adolescents' downward spiraling tendency of depriving themselves of sleep during the week and playing catch-up on the weekend, more research exploring ways to intervene would be beneficial."

jahonline/