Jan 13, 2010Chronic sleep loss severely degrades nighttime performance
New research shows that chronic sleep loss over a few weeks results in much slower reaction times and profoundly poorer performance.
Boston, MA -Although the exact function of sleep is unknown, we do know that sleep is necessary for optimal cognitive
The circadian rhythms and sleep-wake cycles are normally intertwined, so special study conditions are required to tease apart these influences on how well we function. The researchers scheduled nine healthy volunteers to live for three weeks on a schedule consisting of 43 hour "days", each with 33 hours of scheduled wakefulness and 10 hours of scheduled sleep. This equates to 5.6 hour sleep opportunities every 24 hours. They were able to assess the effects of acute sleep loss from long consecutive hours awake, chronic sleep loss from reduced overall sleep over weeks, and the independent cycling of the circadian rhythm.
"Many people have a false sense of reassurance that they can quickly recover from a chronic sleep debt with just one or two days of good sleep. Our work may help explain this: one long night of sleep can restore performance to normal levels for about six hours after waking, and the late afternoon and early evening alerting signal of the circadian rhythm can largely hide the effects of chronic sleep loss during the rest of a normal day," said Daniel Cohen, MD, lead author of the paper and a researcher in the Division of Sleep Medicine at BWH, "However, the lingering effect of chronic sleep loss causes performance to deteriorate dramatically when these individuals stay awake for an extended period of time, for example when they try to pull an ‘all-nighter."
"Individuals who get too little sleep during the work or school week but try to catch up on weekends may not realize that they are accumulating a chronic sleep debt." said Elizabeth Klerman, senior author of the paper and an Associate Professor in the Division of Sleep Medicine at BWH. "This may lead to a dangerous situation in which individuals do not realize the extent of their sleep deprivation and their vulnerability to sudden sleepiness when they try to drive or work late into the night."
"These findings contribute to the growing body of research showing that resident physicians who are required to work in hospitals for 30-hour shifts twice per week often make fatigue-related errors. Burning the candle at both ends at the expense of sleep renders tasks such as driving a truck, operating heavy machinery or performing surgery dangerous, especially during the hours ordinarily reserved for sleep," said Dr. Charles Czeisler, head of the Division of Sleep Medicine at BWH and co-author of the paper.
This work was supported by the Air Force Office of Scientific Research, the National Institutes of Health, and the National Space Biomedical Research Institute.
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