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Caught napping

Q. Ever since I retired last year, I've enjoyed taking an afternoon nap whenever it's convenient. My wife says napping will turn me into an old man. I can easily give up my naps if she's right — but is she?

A. Daytime sleepiness can result from insuffi cient nighttime sleep. Causes range from simply not devoting enough time to sleep to medical problems that impair the quality of sleep; restless legs syndrome, obstructive sleep apnea, and conditions that produce excessive nighttime urination are examples. And in some cases, daytime sleepiness can result from medical problems such as depression or an underactive thyroid.

Fortunately, your situation sounds completely different. People who are sleep deprived feel groggy during the day and may fall asleep when they least want to, perhaps at their desks or behind the wheel. Voluntary napping, on the other hand, is not a sign of sleep deprivation, illness, or aging. In fact, a "power nap" can be helpful as well as enjoyable.

NASA and the Federal Aviation Administration found that strategic naps can help. They studied 200 airline flight crews, each of which conducted eight nine-hour trans-Pacific flights during a span of 12 days. Half the crews stayed awake as usual, while the others took 40-minute naps in rotation. Intensive evaluations showed that napping improved subsequent alertness and performance.

These high-flying conclusions don't stand alone. In fact, many studies in shift workers and other volunteers have reported that a nap as brief as 20 minutes can improve alertness, psychomotor performance, and mood.

Naps, however, can produce problems of their own. One problem is sleep inertia or grogginess and disorientation that may accompany awakening from deep sleep. The second potential problem is nighttime wakefulness.

To get the benefit of a quick snooze without being caught napping, plan to take your nap at a good time in your daily sleep-wake cycle; for many people, sometime between noon and 4 p.m. is best. Don't sleep too long; a 20- to 40-minute nap may refresh your day without keeping you up at night. And give yourself 10 or 15 minutes to wake up fully before you resume a demanding task.

I hope your wife won't lose sleep over my answer. Perhaps the best way to win her over would be to get her to take a nap or two — if she tries it, she may like it.

— Harvey B. Simon, M.D.Editor, Harvard Men's Health Watch