In the largest study to date on the effects of midday snoozing, researchers from the Harvard School of Public Health (HSPH) and the University of Athens Medical School in Greece, tracked 23,681 apparently healthy men and women, ages 20 to 86, for more than six years.
Their findings, published in today's Archives of Internal Medicine: those who took afternoon siestas of 30 minutes or more at least three times a week had a 37 percent lower risk of dying from heart disease than those who did not.
Even more impressive: researchers found that working men who took regular or occasional naps had a 64 percent lower risk of death from heart attacks or other heart-related ills than their nonnapping compeers. And working women? "The apparent effect was evident mainly among working men," says lead study author Dimitrios Trichopoulos. "There were not enough coronary deaths among working women (only six) in this group to allow sound inference." (Of course, some might consider that a positive thing.)
Trichopoulos, a cancer prevention and epidemiology professor at HSPH, says researchers decided to look into this issue, because coronary mortality tends to be low in populations in which the prevalence of siestas tends to be high.
"Our working hypothesis has been that napping may have stress-releasing properties," he says.
Researchers speculate that the extra shut-eye may help reduce chronic stresswhich has been implicated in heart diseaseby giving workers a break from angst-ridden jobs.
Trichopoulos says that if further studies net similar results, "then lifestyle changes that would allow afternoon napping might have to be considered." Of course, that's easier said than done, especially in the United States, where employers are not exactly known to encourage workers to nap. "I am fully aware that the lifestyle in the U.S. does not leave much room for changes of this type," he says.
But afternoon siestas have long been a part of daily life in Greece, where the study took place, as well as in other Mediterranean and some Latin American countries, which tend to have low mortality rates from coronary disease.
The Mediterranean diet, rich in fruits, vegetables, beans and olive oil, has also been credited for keeping a lid on heart disease. Trichopoulos says the study controlled for diet, physical activity and other factors that are predictive of coronary mortality.
He notes that researchers would like to review the data again once there are "more outcomes among men and particularly women.
"No firm conclusions can be drawn on the basis of this study alone, except that the issue is worth further investigation," Trichopoulos says. "Right now, we would only reassure those who take a siesta that this may actually be not simply pleasant and relaxing, but also a healthy habit."
His advice: "For those whose lifestyle allows having a nap, go ahead and do so." No doubt your boss will be thrilled.
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