A Wink on the Job Helps You Think

Study finds people perform better after a nap

By Adam Marcus
HealthScoutNews Reporter

WEDNESDAY, May 29 (HealthScoutNews) -- Practice may make perfect, but not without a nap to recharge the practitioner's batteries.

In a surprising study, researchers have found performance on tests of visual perception wane throughout the day, but as little as 30 minutes of napping can salvage a person's skill. An hour's even better: Sleeping that long in the middle of the day can reverse fatigue-related declines in perception.

The findings, which appear in the June issue of Nature Neuroscience, support workplace napping initiatives that aim to improve productivity by giving employees siesta time.

Researchers have long known that learning ability depends largely on fatigue. People perform much better on tests of mental agility if they've had at least six hours -- and preferably eight -- of shut-eye the night before.

However, how fatigue within a day weighs on performance hasn't been well studied.

In the new work, a team of Harvard University psychologists, led by graduate student Sara Mednick, studied the link between tiring and visual perception in 30 men and women. Ten were permitted no naps during a grueling day's worth of testing, while 10 stole 30 minutes of sleep and 10 others got a full hour.

Over the course of the 10-hour experiment, the subjects performed the task four times.

The volunteers did worse on the second tests than they did on the first. Scores steadily worsened for the 10 people who didn't get to nap during the day, while those who got a half-hour of rest were as sharp on the fourth test as they were on the third round.

More remarkably, the researchers say, people who napped for an hour performed as well on the third and fourth tests as they did on the first. In other words, the brief sleep reversed the early deficit.

"With an hour of sleep in the middle of the day, this fatigue [effect] doesn't actually happen," Mednick says. "The half-hour nap stabilizes you at what ever performance you were at."

Mednick's group was able to show the progressive flagging wasn't merely the result of boredom or general exhaustion. What's not clear, however, is why all three groups suffered the initial loss of skill between the first and second test. "This is the first study to really show that there is a decline in performance," she says.

Darrel Drobnich, senior director for government and transportation affairs at the National Sleep Foundation, says the new study demonstrates what his group already knows: "A short nap does help daytime alertness."

Drowsiness takes a major toll on the nation, Drobnich says. Transportation officials have linked drowsy driving to 100,000 accidents a year, including more than 1,500 deaths and 71,000 injuries. The sleep group estimates that daytime sleepiness is a $100 billion drag on the nation's economy, in the form of lost productivity, workplace injuries, health-care expenses and other outlays.

Recognizing the value of a well-rested workforce, a small but growing number of businesses have started offering their workers napping rooms.

Yarde Metals of Bristol, Conn., is among them. For the past three years, the metal distributor has been encouraging its 450 employees to take daily naps. It now has napping rooms at each of its six facilities, where workers can doze for 20 minutes on couches, says Susan Kozikowski, Yarde's marketing manger.

Kozikowski says that while she doesn't know if the policy has led to gains in productivity and slashed on-the-job injuries, it has given morale a boost. So, too, have other perks to please employees, including an on-site health club, a basketball court, and the latest addition -- a dog kennel for workers' pets, she adds.

What To Do

For more on the importance of a good night's sleep, try the National Sleep Foundation. And for more on napping at work, try National Workplace Napping Day.

SOURCES: Sara Mednick, M.A., Harvard University, Cambridge, Mass.; Darrel Drobnich, senior director, government and transportation affairs, National Sleep Foundation, Washington, D.C.; Susan Kozikowski, marketing manger, Yarde Metals, Bristol, Conn.; June 2002 Nature Neuroscience

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