A nap may give your heart a rest

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A nap may give your heart a rest

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A light afternoon nap may provide a soothing biological benefit.

For well-rested, healthy people, an actual siesta instead of just

relaxing seems to lower blood pressure. But it's best not to doze

off for too long.

By Brink, Los Angeles Times Staff Writer

October 22, 2007

The next time the boss finds you leaning back in your chair, feet

up, eyes shut, tell her that you're napping for medicinal purposes.

Science won't definitively back you up yet, but the evidence is

mounting that a short, afternoon nap, for an otherwise well-rested,

healthy person, is good for the heart. " I love to nap, " says Dr.

Downey III, chief of sleep medicine at Loma University

Medical Center. " I recommend napping. "

Among his fellow researchers, it's still controversial whether

napping has cardiovascular benefits. Early studies of possible heart

benefits of siestas in Mediterranean and LatinAmerican countries,

where short afternoon naps are typical, have had mixed results. But

a recent large study of 23,000 people in Greece, published in the

Feb. 12, 2007, Archives of Internal Medicine, showed a 37% reduction

in heart attacks among people who napped at least three times a week

for a minimum of 30 minutes. That study was the first to weed out

sick and sedentary nappers and control for physical activity and

diet, which may have colored results of other studies showing no

benefit.

Now a study, in the Oct. 15 online edition of the Journal of Applied

Physiology, offers a clue about why a nap might be good.

The new study tested nine healthy volunteers who did not usually

nap. After sleeping for four hours the night before, each was hooked

up to check for blood pressure under three conditions. In two

sessions the volunteers relaxed, one time standing and once lying

down, but didn't sleep. In the third session, the subjects fell

asleep for no more than an hour.

The researchers found a significant drop in blood pressure when the

volunteers slept, but not when they merely relaxed. And the drop in

blood pressure when they napped occurred in that sleepy window of

time right before falling asleep, not during the nap itself.

It's the brief period of anticipation of the coming snooze where

cardiovascular benefits take place. Just lying awake, even if

relaxed, doesn't do the trick, says Greg Atkinson, chronobiologist

with the Research Institute for Sport and Exercise Sciences at

Liverpool s University, and an author of the study.

That makes sense to Downey. " Anything you gain in [a restful state]

would be magnified by going to sleep, " he says. But he cautions that

for a nap to result in increased alertness, it should probably last

20 to 30 minutes.

" With a light nap, you get that soothing, biological benefit, but

you don't have to fight your way back to consciousness, " he says.

That's because brain waves slow considerably as you get drowsy, more

so when you sleep. But after about 30 or 40 minutes, the brain goes

into still-deeper sleep, and waking can make a person feel more

groggy than rested.

Younger children, and adults who are sleep deprived, go into deeper

states of sleep quicker, so a short nap for them might be more

likely to result in a groggy awakening. And insomniacs are generally

advised not to nap, Downey says, to give them a better shot at

sleeping at night.

Inadequate sleep -- seven to eight hours is recommended for the

average adult -- as well as disorders such as sleep apnea are

pervasive in American society, and people who feel sleepy throughout

the day should talk to their physician, says Twery, director

of the National Center on Sleep Disorders Research at the National

Heart Lung and Blood Institute. " If sleepiness is affecting what

they do, controlling their lives, or if they wake up with morning

headaches, maybe they need a medical evaluation, " he says.

But for healthy people who get a good night's sleep, the human

circadian clock is set to want a brief nap in the early afternoon.

It feels good, and it just might be good for the heart, to indulge

that post-lunch loss of energy. Go ahead. Put your feet up and close

your eyes.