Study ties drop in deaths to a little nap after lunch
Could midday napping save your life?
If the experience of Greek men is any guide, the answer just may be yes.
In a study released yesterday, researchers at the Harvard School of Public Health and in Athens reported that Greeks who took regular 30-minute siestas were 37 percent less likely to die of heart disease over a six-year period than those who never napped. The scientists tracked more than 23,000 adults, 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 been intrigued by the potential role of napping.
The study, published in the Archives of Internal Medicine, concluded that napping was more likely than diet or physical activity to lower the incidence of heart attacks and other life-ending heart ailments.
Still, the authors cautioned that further research is needed to confirm their findings.
"We don't want the world to start sleeping in the afternoon yet. A single study never conveys a public health message," said Dr. Dimitrios Trichopoulos , a Harvard professor and author of the study, who says he stopped napping when he moved to the United States 20 years ago.
Specialists not involved with the study said there are sound biochemical reasons to believe that a nap may help protect against heart disease.
Essentially, they said, sleep at any time of day acts like a valve to release the stress of everyday life. Blood pressure is reduced and heart rates slow. At the same time, the immune system shores itself up. Increasingly, researchers are recognizing the role the immune system plays in heart disease.
"We all know that the three pillars of health are diet, exercise, and sleep, and, sometimes, people forget about the importance of sleep," said Dr. Alex Chediak , president-elect of the American Academy of Sleep Medicine and a University of Miami researcher.
Nighttime sleep has been much more thoroughly studied than napping. But researchers assumed that the benefits of nighttime sleep accrue from naps as well.
The study released yesterday is believed to be the largest ever to examine the link between napping and health. Napping, researchers believe, allows people a chance to reset their heart rates and blood pressure in the middle of the day.
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. It was that group that derived the greatest benefit, with a coronary death rate substantially lower than Greeks who didn't nap. The effect was far more modest among those who napped only occasionally, and was not considered statistically meaningful.
The researchers said that while working men appeared to benefit the most from naps, they could not reach any conclusions for working women because there were relatively few in the study.
For retirees, siestas did not lower heart-disease risk.
There's a well-recognized biological impetus for the desire to take a break midway through the waking hours: Our bodies tell us to, said Michael Twery , director of the federal government's National Center on Sleep Disorders Research . Drowsiness recurs right before bedtime.
"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 ranked as the nation's number one killer, specialists said the Harvard study should give rise to more definitive nap 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 cardiovascular specialist at the University of California at Los Angeles. "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."
In the 24/7-pressure cooker of American society, it is unlikely that many employers -- or workers, for that matter -- will embrace a 30- minute nap during the workday, sleep specialists acknowledged. If anything, they said, countries where napping has been part of the culture, notably Spain, have increasingly abandoned the practice.
But there are a few places left that champion the midday nap. At a New England company called Yarde Metals Inc., in Southington, Conn., the nap room was upgraded last week to include a full-body massage chair that incorporates aromatherapy and motion. It can simulate the sounds and sights of a beach or a babbling brook.
"It leads to improved safety," said marketing director Susan Kozikowski .
But even if workplace napping is unlikely to become widespread in the United States, there is something to be learned from the siesta study, said Dr. Michael Irwin , a sleep specialist at UCLA's Semel Institute for Neuroscience .
"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," Irwin said. " Sleep is a behavior we can control as humans, and if we do that, our overall health will improve. "
Stephen Smith can be reached at firstname.lastname@example.org.