Sleep Deprivation Affects Cognition Upon Awakening

Cognitive performance doesn't recover until 21 to 61 minutes later, researchers find

TUESDAY, Jan. 10 (HealthDay News) -- Cognitive function in sleep-deprived subjects is significantly worse immediately upon awakening than it is later in the day, according to a study published in the Jan. 11 issue of the Journal of the American Medical Association.

Kenneth P. Wright, Jr., Ph.D., of the University of Colorado in Boulder, and colleagues compared the effects of sleep deprivation in nine paid volunteers (eight men and one woman), aged 20 to 41, who had no medical, psychiatric or sleep disorders. The study participants slept about eight hours a night for three weeks, and then were sleep deprived for 26 hours. After the subjects slept, the researchers began cognitive testing a mean of 73 seconds after the subjects awoke.

The subjects' cognitive performance immediately on awakening was worse than performance at all subsequent points measured across 26 hours of sleep deprivation, with a mean of 65% of peak performance. Between 21 and 61 minutes of wakefulness, the mean cognitive performance ranged from 83% to 86% of peak performance and was not significantly different from performance at subsequent points. The researchers found no significant performance differences when comparing the female participant to the male participants.

"The present results may have important implications for occupations in which sleep-deprived personnel are expected to perform immediately on awakening from deep sleep, including physicians, truck drivers and pilots arising from on-board sleeper berths, and public safety and military personnel," the authors conclude.

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