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« MIT professor says he's lost 14 pounds during hunger strike | Main

Monday, February 12, 2007

The lifesaving potential of an afternoon nap

By Stephen Smith, Globe Staff

Could a midday nap save your life?

If the experience of Greek men is any guide, then the answer just may be yes.

In a study released today, researchers from the Harvard School of Public Health and in Athens report that Greeks who took regular siestas were 37 percent less likely to die of heart disease than those who never indulged in a midday slumber. The scientists tracked more than 23,000 adults for an average of six years, finding that the benefits of napping were most pronounced for working men.

Researchers have long recognized that Mediterranean adults die of heart disease at a rate lower than Americans and Northern Europeans. Diets rich in olive oil and other heart-healthy foods have received some of the credit, but scientists have long been intrigued by the potential role of napping.

After taking into account other potential explanations, including physical activity and diet, the article appearing in the Archives of Internal Medicine concludes that napping habits were the most likely explanation for the lower rate of heart attacks and other life-ending heart ailments.

Still, authors of the study cautioned that theirs is a single study and that further research is needed to confirm their findings.

"We don't want the world to start sleeping in the afternoon yet," said Dr. Dimitrios Trichopoulos, a Harvard professor and author of the study. "A single study never conveys a public health message."

Trichopoulos.jpg
Dr. Dimitrios Trichopoulos

Specialists not involved with the study concurred in that sentiment but also said there are sound biochemical reasons to believe that a nap may confer protection against heart disease.

When we sleep, the body is rejuvenated. For example, blood pressure and heart rates slow. At the same time, the immune system regains some of its strength and, increasingly, researchers recognize the role that the immune system plays in heart disease. Essentially, a nap acts like a valve to release the stress of every-day life.

But specialists also acknowledge that in the 24/7 pressure cooker of American society, it's not likely that too many employers -- or their workers, for that matter -- are going to embrace a 30- or 45-minute nap anytime soon.

"So, to me, the take-home message is we do need a good night's sleep, we do need to look at how much sleep we get and optimize that," said Dr. Michael Irwin, a sleep specialist at the Semel Institute for Neuroscience at the University of California at Los Angeles.

The study is believed to be the largest ever to track the link between napping and its effect on health. The researchers quizzed study participants about their siesta habits, defining regular nappers as those who took a midday break at least three times a week, with the nap lasting a minimum of 30 minutes.

And it was that group that derived the greatest benefit, with a 37 percent drop in deaths attributable to heart disease. The effect was far more modest -- 12 percent -- among those who napped only occasionally, a reduction not considered statistically significant.

The researchers said that while working men appeared to benefit the most from naps, no comparable conclusion could be reached regarding working women because there were relatively few in the study. For retirees, siestas did not lower heart-disease risk.

There's a strong biological impetus for the desire to take a midday break: Our bodies tell us to, Michael Twery, director of the federal government's National Center on Sleep Disorders Research.

"The human biological clock has two cycles each day, with two dips," Twery said. "One of those dips occurs shortly after lunch for most people. This is a period when many people feel perhaps a little sleepy, drowsy, less awake."

Napping has historically received scant attention from researchers, but with heart disease still ranked as the nation's number one killer, specialists said the Harvard study should give rise to further siesta research.

"Given how prevalent cardiovascular disease is, any intervention that could effectively lower risk would be welcomed and worthy of further study," said Dr. Gregg Fonarow, a UCLA specialist in cardiovascular medicine. "The challenge now is how people read this. If they read it as, 'I can continue to smoke, not eat healthy, not exercise and just take a nap in the afternoon and be protected from cardiovascular disease,' then that is absolutely not the right message to be sending."

Some companies already allow on-the-job naps, and many workers say it makes them more, not less, productive.

Yarde Metals, a metals distributing firm, built a nap room at its Southington, Conn., headquarters as part of an employee wellness program. With two leather sofas, fluffy pillows, soft lighting and an alarm clock, it's the perfect place for a quick snooze, engineer Mark Ekenbarger said.

Ekenbarger, 56, has an enlarged heart artery and said he frequently takes half-hour naps on the advice of his doctor to reduce stress.

"It really does energize me for the rest of the day," Ekenbarger said.

"It would be really encouraging if employers across the country really embraced that philosophy that napping is a good thing," he said. "It makes a big difference in my life."

Material from the Associated Press was used in this report.

Stephen Smith can be reached at stsmith@globe.com.

Posted by Karen Weintraub at 01:31 PM
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