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SEATTLE -- Laboratory experiments indicate that adolescents who are deprived of sleep function poorly on school days, and their recovery on the weekend is not enough to make up for burning the midnight oil during the week, researchers said here.

Lapses in psychomotor vigilance tests increased (P<0.001) and subjective scores on the Karolinska Sleepiness Scale increased (P<0.001) after the adolescents had undergone sleep deprivation -- 5 hours of sleep instead of 10, reported and research assistant at the University of South Australia Centre for Sleep, Adelaide.

In her oral presentation at the annual meeting of the Associated Professional Sleep Societies, Agostini said that while the young participants said they felt refreshed after having 10 hours of sleep -- and their subjective sleepiness scores returned to baseline, their psychomotor test scores did not recover to baseline levels.

"These adolescents were unaware that their functioning was still diminished," she told MedPage Today. "We found that adolescents are chronically sleep deprived."

"Sleep restriction is detrimental to adolescents' response times, ability to sustain attention, and perceived sleepiness," Agostini said. "Thus, across a school week, adolescents can accumulate a substantial sleep debt that may have meaningful, negative implications for school performance.

"Furthermore, weekend recovery sleep may not be adequate to overcome deficits incurred through the week," she said.

"There are serious clinical implications to this work," said professor of psychology at the University of Montreal and co-moderator of the session at which Agostini presented her research. "We have to make sleep a first priority," she said.

"We have to convince adolescents that they need sleep in order to perform well in school -- and for their safety when they are driving," she said. "They have to get sleep."

Agostini said that there are long-term implications to sleep deprivation in these adolescents. "This could result in academic underachievement which has been linked to unemployment and low paid employment," she said.

She said that because of biological and psychosocial factors adolescents are more likely to try to catch up with sleep by sleeping in, rather than going to bed early. She noted that some school systems have tried to accommodate these findings by starting school later, but it had not become a widespread practice.

"Negative effects of sleep restriction on daytime functioning in adults are documented; however, the time course and severity of deficits in sustained attention and response times associated with sleep restriction are little studied in adolescents," she said in explaining the motivation for her work.

For the study, conducted over 10 days in the sleep laboratory, the researchers recruited 12 adolescents (six girls), ages 15 to 17. After one adaptation night and one baseline night in which the lights went out at 9:30 p.m. and came on at 7:30 a.m. -- a 10 hour sleep period -- time in bed was restricted to 5 hours for the next 5 nights, representative of a typical school week. On those nights, lights out was at 2:30 a.m. and lights on was at 7:30 a.m.

Those 5 nights were again followed by two nights of 10 hours of sleep to allow for sleep recovery.

The subjects performed the 10-minute psychomotor vigilance test, which measured response time. The participants were also asked to judge their own sleepiness. The tests were performed five times daily at 3-hour intervals, beginning 1 hour after awakening.

Agostini noted that, surprisingly, the first psychomotor tests done an hour after wakening proved to be the worst performance. All three of the tests showed significant declines during the sleep deprivation period and continued to lag behind baseline measurements in the recovery period -- except for the adolescents' subjective belief that that were as good as their baseline scores.

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