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."
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.
Nap early and often
Along with boosting creativity and productivity, employees who nap may be able to fill their "sleep banks" to prepare for times when they are likely to fall short on slumber, research shows.
"We used to think that you couldn't bank sleep," says Balkin. "But our latest research shows that getting extra sleep in the form of a nap can improve alertness and performance later, when people experience sleep loss." Balkin says he now advises soldiers in the field "to nap early and often" if they are getting ready to go out on a mission.
But does an afternoon nap rob you of sleep at night? It's a reasonable concern, especially among older people, since the amount of sleep people need declines with age. "If you needed eight hours when you were in your 30s, you may get along just fine and function well with just six and a half hours when you're in your 60s," says Timothy A. Roehrs, a sleep researcher at Henry Ford Hospital in Detroit.
But while some findings do suggest that napping can interfere with nighttime slumber, others find no effect. In a 2011 study published in the Journal of the American Geriatric Society, sleep researchers at Weill Cornell Medical College in White Plains, N.Y., asked a group of 22 older adults to take a daily nap. After a month, volunteers had added to their total sleep time without compromising the quality of their nighttime slumber. What's more, napping improved their scores on several memory and mental processing tests.
"I think most of us agree it's wise to avoid taking a nap too close to bedtime, which may make it harder to fall asleep at night," says Roehrs. In general, the best time to nap is between 1 p.m. and 4 p.m., when the body's 24-hour circadian rhythm normally experiences a lull that makes it easier to snooze.
How long you nap may also be important in determining the benefits you get. A 20-minute nap can help restore alertness and energy, says McDevitt. But if you want to take advantage of the memory and performance-enhancing benefits of a nap, research suggests you'll need to experience rapid-eye movement (REM) sleep. For that, you'll need to take a 60-minute siesta. Napping much longer than that doesn't add additional benefits and may make you feel groggy. The phenomenon, which sleep researchers call "sleep inertia," occurs because the brain chemicals that help you stay asleep in spite of barking dogs and sirens in the night take time to clear out.
"The longer you nap, the stronger sleep inertia is likely to be," says Michael V. Vitiello, professor of psychiatry and behavioral sciences at the University of Washington. If you tend to feel groggy after napping, he says, it's wise to give yourself time to wake up fully before driving or doing other tasks that require concentration. A cup of caffeinated coffee can help clear away the cobwebs.
Not for everyone
Despite the multiple studies that link napping to health benefits, some findings have raised red flags. Older people who nap tend to have more health problems than non-nappers, says Vitiello. Perhaps that's not surprising. People with health problems may also be more likely to get tired during the day. Problems such as depression, nocturia (having to get up at night to urinate) and sleep apnea can get in the way of a good night's sleep.
And napping can exacerbate insomnia. Feeling sleepy in the afternoon is perfectly normal. But if you toss and turn at night and feel tired in the morning, says Roehrs, napping may not be the best idea. Indeed, one of the treatments for chronic insomnia is sleep restriction, which involves spending less time in bed in order to improve the quality of sleep.
For most of us, however, napping is perfectly OK. If you're new to napping, says Vitiello, go ahead and give it a try. "Experiment with different length naps. If you feel more refreshed, great. If not, maybe napping isn't for you," says Vitiello.
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