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For years, Americans have been bombarded with the media message that the culture has become sleep deprived—too many people logging too few hours of rest.
But while some people truly don’t get enough sleep, USC exercise science assistant professor Shawn Youngstedt thinks the sleep deprivation message has been overstated, and that the risks associated with too much sleep are at least as great as the risks of insufficient sleep.
“There have been 18 epidemiological studies that have shown a correlation between higher mortality rates and too much sleep—eight hours or more in bed,” Youngstedt said. “The data can’t prove that long sleep is the cause of higher mortality, but there definitely is a correlation, and a whole lot more people sleep eight or more hours than sleep six or less hours per night.”
Youngstedt is using a three-year grant from the National Institutes of Health to investigate what happens when chronic sleepers try to reduce their time in bed. He’s studying 50 subjects—all of them from 50 to 70 years of age—who report sleeping at least eight and a half hours per day.
“We are having volunteers reduce their time in bed by 90 minutes per night for eight weeks, and we’re looking for possible negative consequences such as mood shifts, sleepiness, and declines in reaction time, memory, and vigilance,” he said.
“We think that the reduced time in bed might not only have no negative consequences, but it might actually have positive consequences such as helping consolidate their night-time sleep and promoting daytime functioning.”
For those who think it counterintuitive that a person can actually sleep too long, Youngstedt offers a simple analogy: it’s possible to get too much exercise, too much sunlight exposure, or to consume too many calories. “So just because we sleep in for 10 hours on a Saturday morning doesn’t mean that our bodies actually ‘needed’ those extra winks, any more than we actually ‘needed’ those extra calories at the buffet,” he said.
So far, Youngstedt and his research team have completed the eight-week studies with several small groups of volunteers. Some of the reduced-time sleepers have maintained their new schedules; others have reverted to their long-snoring ways. Few negative consequences of reduced sleeping time have been found, he said.
More volunteers for the study still are needed. They should be 50 to 70 years in age and regularly sleep at least eight and a half hours daily. To volunteer, call Youngstedt at 803-777-9929 or e-mail him at syoungstedt@sc.edu.
January 2005
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