Regular midday naps (siestas) by workers may reduce the risk of dying from heart disease, according to a study by researchers from the Harvard School of Public Health (HSPH) and the University of Athens Medical School (UAMS) in Greece.

The study appears in the February 12, 2007, issue of The Archives of Internal Medicine.

The researchers looked at 23,681 individuals living in Greece who, at the beginning of the study, had no history of coronary heart disease, stroke, or cancer.

The study participants were followed for an average of 6.3 years. Siestas are common in the Mediterranean region and several Latin American countries and those countries also tend to have low mortality rates of coronary heart disease.

The results of the study showed that people who regularly took siestas, defined by the researchers as napping at least three times per week for an average of at least 30 minutes, had a 37 percent lower coronary mortality than those not taking siestas. Occasional nappers showed a statistically non-significant 12 percent reduction in coronary mortality.

The apparent protective effect of siestas was particularly strong among working men and weaker among those not working, mainly retirees. Among working women, there were too few deaths to draw conclusions.

The study's authors believe that an afternoon siesta in a healthy individual may act as a stress-releasing process, since there is considerable evidence that stress has both short and long term adverse effects on incidence of and mortality from coronary heart disease. The fact that the association was more evident among working men compared to retirees apparently reflects the different stress levels with which these subgroups have to cope, according to the researchers.