Nap, or not?

Napping during the day can make it more difficult to sleep at night, and some studies suggest that people who sleep during the day tend to be less healthy.

For these reasons, the American Academy of Sleep Medicine cautions adults to avoid napping and to focus on getting a solid block of seven or eight hours of sleep at night (teens need about nine hours).

But a number of recent studies suggest that a brief daily siesta can compensate for lost sleep, improving alertness and possibly providing some health benefits of nighttime snoozing.

Greek researchers made headlines last year when they reported that regular nappers gain protection from heart disease. They tracked more than 23,000 men and women for six years and found 37 percent fewer heart disease deaths among those who took a daily snooze.

Napping worked better than caffeine at restoring alertness and memory after sleep deprivation, in a study published in May by the University of California at San Diego and the Veterans Affairs San Diego Healthcare System.

“A 10-minute nap is surprisingly effective, even in people who are significantly sleep deprived,” says Richard Jennings, a professor of psychiatry and psychology at the University of Pittsburgh School of Medicine.

The benefits of napping, says sleep medicine specialist Ronald Kramer, depend on the situation. People in their 60s and older, who often struggle to sleep more than six hours a night, are likely to benefit from a daily 30- to 60-minute nap, he says.

For younger people whose schedules get in the way of sleeping more than seven hours a night, Kramer says taking a 10- or 15-minute nap after lunch can be good. But, “if you feel worse after a power nap, you are probably not getting enough sleep at night.”

A nap’s length makes a difference. Australian researchers compared naps lasting five, 10, 20 and 30 minutes on volunteers restricted to about five hours of sleep the night before. After subjects napped, researchers rated their sleepiness and tested their ability to think clearly and react quickly.

The shortest naps proved no better than no nap. The longest naps left subjects groggy, a state that took more than an hour to dissipate. The 20-minute nap helped people perform better on most tests, but the gains took about 35 minutes to emerge after waking.

The 10-minute nap, in contrast, produced improvement in every test of sleepiness and mental alertness immediately after waking.

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