Best Strategy for Last-minute Study
Scripps Howard News Service - June 02, 2003

OK, so the project's due tomorrow morning, or the big test is looming. You know you've got to burn the candle late, but still get enough sleep to function efficiently the next day. What's the best strategy?

Researchers at Stanford University Medical Center have come up with what seems to be the best sleep formula for a bad situation: go to bed in the wee hours and get up about the regular time, rather than going to bed earlier and getting up hours before dawn.

"The results were surprising," said Dr. Christian Guilleminault, a professor of psychiatry and behavioral sciences who led the study. "We had suspected that the more sleep-restricted the participants were, the sleepier they would be, regardless of when they went to bed. That's not exactly what we found."

Sleep researchers, like most of us, know that losing sleep over time causes decreased daytime functioning and a lower quality of life. Different people tolerate less sleep differently for a lot of reasons, but the effect of the exact time that sleep took place hadn't been studied before the Stanford group's work, published in the May issue of the journal Sleep Medicine.

The study involved eight men, aged 18 to 25, who were monitored as they slept 8.5 hours for two nights, then were split into two groups: one foursome was allowed to sleep from 10:30 p.m. to 2:30 a.m. for seven nights, the other from 2:15 a.m. to 6:15 a.m.

They spent the entire week in the lab, where the researchers measured behavior and wakefulness though a series of tests, including one that asked them not to fall asleep, another that simulated driving.

Sleep restriction affected all the study subjects, and the results of tests taken the date after each got 8.5 hours of sleep differed greatly from those after the last night of sleep deprivation.

But the early-morning sleep group's score on maintaining wakefulness was significantly better than the late-night sleep group. Researchers noted that the early-morning group slept more efficiently (had more time actually asleep during the assigned window) and spent less time falling asleep than those assigned earlier to bed and rise.

Guilleminault said data from other tests is still being evaluated, but the preliminary findings warrant further studies. The sleep timing issue could be particularly important for the military and emergency workers who must work around sleep deprivation for long stretches at a time.

Aside from the impact of sleep timing, he said the most striking part of the study was great differences in how individual subjects respond to sleep deprivation.

One member of the early-morning sleep group did not seem to be affected by the four-hour nights until the sixth day of the test; until then he functioned at "borderline normal" levels.

But a participant of the late-night sleep group reacted so poorly to his new schedule that he developed severe insomnia during the hours he was supposed to snooze.

"What we show is that everyone becomes impaired by sleep deprivation, and abnormal responses are triggered in some people, which is good reason for anyone to be cautious about limiting their amount of sleep," Guilleminault said.

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Last updated: 06/05/2003 - 07:14 PM