Taking too many naps linked to heart attack, study says

Could napping help you avoid heart attack and stroke? Researchers thought so -- although a new study published in the British Medical Journal says too many naps per week are a bad idea when it comes to lowering the risk of cardiovascular disease.

More than 3,000 people studied by the University of Lausanne in Switzerland were grouped based on the number of naps they reported taking every week. Most never napped, some said they napped one or two times weekly, and others termed "frequent nappers" took a snooze three or more times per week. Those with the fewest heart attacks? They were the one to two times weekly nappers. Second place went to the group who never took naps. People who napped nearly every day had the most heart attacks and strokes during the study period.

Both heart attack and stroke are caused by cardiovascular disease, also called heart disease, when plaques slowly build up in the vessels supplying blood to the heart, eventually blocking blood flow or causing clots.

But napping research isn't new. Other studies have revealed that Greeks, who boast some of the lowest rates of heart disease in the world, had a lower risk of death from heart attack if they reported napping. Yet research had only compared nappers versus non-nappers, never considering how many naps people were taking each week.

In the new Swiss study, "frequent nappers" were mostly older men with less education, higher body mass, and a greater tendency to smoke. Even when the research took these lifestyle factors into account, people napping once or twice weekly still had less risk of heart attack or stroke.

When it comes to naps, "it might not only be the duration, but also the frequency that matters," Drs. Kristine Yaffe and Yue Leng of the University of California at San Francisco said in an editorial that went with the study.

The authors had cited other research showing naps more than one hour long may actually increase cardiovascular risk, though their own research did not correlate longer naps with higher risk of a cardiac event.

But before requesting naptime at work, remember that the most important risks for heart attack are smoking cigarettes and having untreated high blood pressure, diabetes and obesity.

Dr. Jennifer Haythe, a cardiologist at Columbia University, pointed out some limitations of the study, telling ABC News that it "was conducted on a Swiss population and it is unclear if this is a generalizable result." Dr. Haythe adds that although she wouldn't give sleep recommendations to patients based only on this study, she does talk to patients about the role of sleep quality in heart health.

Drs. Yaffe and Leng seemed to have a similar perspective in the editorial, adding that "while the exact physiological pathways linking daytime napping to [cardiovascular disease] risk is not clear, [the study] contributes to the ongoing debate on the health implications of napping."

Even within the limits of this small study, a nap could be worth considering -- just not too often. Naps aside, making healthier lifestyle choices like quitting smoking and maintaining a healthy weight should be a daily thought for all people as the dangers of heart disease loom.

Dr. Kendrick is a family physician with the ABC News Medical Unit. She is a member of the American Academy of Family Physicians.