En español | "You must sleep sometime between lunch and dinner, and no halfway measures," wrote Winston Churchill. "Take off your clothes and get into bed. That's what I always do … You will be able to accomplish more. You get two days in one — well, at least one and a half."

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Take a nap. It's good for your health! — Thomas Odulate/Getty Images

Like Churchill, a lot of us are dedicated nappers. In fact, the older we get, the more likely we are to nap. Surveys show that more than half of people 75 and older nap at least twice a week.

That may seem like an innocent enough pleasure. But for decades researchers have been studying napping to understand how it affects everything from health to nighttime sleep patterns, and a few studies have raised red flags, including one that linked napping to health problems. New findings, however, bring much good news, including that napping is associated with a sharper mind.

"For most people, napping is perfectly healthy, and it may even have important benefits," says Thomas J. Balkin, director of the behavioral biology branch at Walter Reed Army Institute of Research. To take advantage of those benefits, though, it's important to know when and how long to snooze.

Enhanced visual learning. "Typically during the day, people's performance on visual learning tests deteriorate," says Elizabeth McDevitt, a researcher at the University of California, Riverside, who is pursuing her doctorate in sleep studies. "We've found that when people nap, their performance doesn't deteriorate, and often even improves after a nap."

Improved memory. During a nap, says McDevitt, the brain seems to consolidate learning. She suspects that napping could be helpful for older people as a way to counteract age-related memory loss, although studies haven't yet looked at the question.

Better problem solving. A nap's ability to boost mental processes could be useful for people such as air traffic controllers and military personnel. Indeed, a study conducted at NASA on military pilots and astronauts found that a 40-minute nap improved overall performance by 34 percent and alertness by 100 percent. As an added benefit, research also suggests that a nap can improve scores on tests of creative problem solving.

Small wonder a growing number of companies now encourage napping, according to Businessweek. Along with gyms and meditation rooms, Google offers employees "napping pods" where they can grab a little shut-eye. Online retailer Zappos provides napping rooms with old-fashioned couches. DeLoitte Consulting has set aside napping rooms furnished not only with comfy couches but also with black-out shades.

Next: Nap early and often. »