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Morning sleepers have an advantage over their late-night counterparts, according to a new study by Stanford University Medical Center.
The study on the effects of sleep deprivation found that individual tolerance of sleep restriction varies widely but that participants had a better adaptation to early morning sleep.
Researchers have long known that a persistent reduction in nightly sleep results in decreased daytime functioning. The Stanford study was the first to examine the effect that the time of sleeping had on participants.
The study involved eight men, 18 to 25 years old. Researchers monitored the participants' sleep and collected base-line data as they slept for 8 1/2 hours for two nights. Then men were split: One group slept from 10:30 p.m. to 2:30 a.m. for seven nights; the other group from 2:15 a.m. to 6:15 a.m. The men's behavior and wakefulness were tracked through a series of tests.
Researchers found that sleep restriction affected all participants, but the results differed between the two groups, suggesting that the timing of sleep might affect daytime function.
The early morning sleep group's score on the wakefulness test was significantly better than the late-night sleep group, indicating that early morning sleepers overall were more tolerant of sleep restriction. And the researchers found that participants in the early morning sleep group had better rates of sleep efficiency (the percentage of time spent sleeping in the four-hour window) and sleep latency (the amount of time spent falling asleep).
SOURCE: Stanford University Medical Center
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Edited and compiled by Ray Walker.
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(c) 2003, Fort Worth Star-Telegram. Distributed by Knight Ridder/Tribune News Service.
