Taking a nap after lunch may be good for your heart. This splendid news arrived in the form of a study published Monday in The Archives of Internal Medicine.

In a study of more than 23,000 Greek men and women ages 20 to 86, researchers found that napping at least three times a week for a half-hour was associated with a significantly decreased risk of death from heart disease. After controlling for factors like smoking, body mass index, physical activity and diet, the researchers found that people who regularly took a siesta had a 37 percent lower coronary death rate than those who never napped. The effect was even greater in working men.

Dr. Dimitrios Trichopoulos, the senior author of the study and a professor of cancer prevention at the Harvard School of Public Health, acknowledged that the study included only a small number of people who had died of coronary artery disease, and that the results when women were analyzed separately, while suggestive of some effect, were not conclusive.

Still, he said, for him a siesta is an absolute requirement.

“If you can, you should take a daily nap,” he said. “I’m Greek. I came to this country in 1989, and I served as chairman of a department at Harvard for seven years. But I always stopped and took a nap every day. If you’re really committed, you do that. It’s such a pleasant custom. You can start your day all over again at 6 or 7 o’clock.”

The researchers began enrolling people in the study in 1994, and followed them for an average of more than six years. They excluded anyone who reported any previous coronary artery disease, chest pain, stroke or cancer, leaving 9,569 men and 14,112 women in the group they analyzed. During the course of the study, 85 men and 48 women died from coronary artery disease.

Napping fewer than three times a week was also associated with reduced risk, but the effect was not statistically significant. When the researchers restricted the analysis to working men who napped regularly, they found a 50 percent reduction, but there were not enough deaths among working women to draw conclusions about them as a separate group.

The idea that naps might be associated with decreased mortality from heart disease, the authors write, was suggested by the high prevalence of siestas in Mediterranean and certain Central American countries where there are low rates of heart disease. But previous studies have shown that in these countries the healthy diet, high in fiber and monounsaturated fat and low in meat and dairy products, is also a predictor of reduced mortality from heart disease. To control for this, the researchers assigned all the participants a score based on how closely they followed that healthy diet.

According to the researchers, there are two other major problems that can distort results in a study like this. First, people who take midday naps are likely to have lower levels of physical activity, and lack of exercise is a predictor of heart disease. Second, people who have a serious condition like coronary heart disease tend to take more naps during the day than others. So attaining firm and unbiased results requires large prospective studies that accurately measure physical exercise and that exclude people who have serious diseases. This study, Dr. Trichopoulos said, met those requirements.

Still, while he did not recommend a nap as a substitute for other healthy behavior, Dr. Trichopoulos said that the observed effect was quite large.

Dr. Henry S. Cabin, a professor of medicine at Yale and director of the Yale-New Haven Hospital Heart Center, expressed a degree of skepticism.

“This study seems to be reasonably well done,” he said, “but maybe that ability to take a nap is a marker of a different kind of lifestyle that itself reduces risk. Maybe leading a more leisurely life is the message, rather than running home to take a nap.”

Dr. Trichopoulos said the study suggested “an effect of the same order of magnitude as taking an aspirin or exercising every day.”

“We want to have these findings confirmed, but if it turns out to be right, this is very significant,” he said. “Napping is much more pleasant than taking an aspirin, and — this is between you and me — much more pleasant than exercising.”