Sleeping your way to heart health

A new Harvard School of Public Health study indicates that there’s more than just olive oil and red wine keeping heart disease rates down in Mediterranean countries. There’s the naps, too.

A study that followed more than 23,000 people for six years showed that regular napping can cut deaths from heart disease by as much as 37 percent, providing a benefit in the same order of magnitude as that linked to lowering cholesterol, eating a healthy diet, or exercising.

“If confirmed by other investigations, these results would imply that a siesta could be added to the several means available for the control of coronary heart mortality, like healthy diets or cholesterol-lowering medications,” said Dimitrios Trichopoulos, the Vincent L. Gregory Professor of Cancer Prevention and the study’s senior author. “The magnitude of the effect appears to be considerable.”

The study, published in the Feb. 12 issue of the Archives of Internal Medicine, was conducted by Trichopoulos and lead author Androniki Naska of the University of Athens Medical School, along with colleagues from the University of Athens and the Hellenic Health Foundation.

Trichopoulos, whose research focuses on hormone-dependent cancers, said he tackled the link between coronary heart disease and midday naps out of intellectual curiosity. Heart disease rates are lower in Mediterranean and Latin American countries. While the differences between the Western diet and diet in those areas has been explored, the cultural acceptance of a midday nap or siesta hadn’t received adequate attention, Trichopoulos said.

In Trichopoulos’ native Greece, it is typical for people to live fairly close to their workplace and to take a several-hour break in the middle of the day. That allows for a midday meal – typically the day’s largest – and for a bit of shut-eye afterward.

Though there have been several studies of the effects of napping and of “sleepiness,” their results have been conflicting and, in some cases, may have been influenced by other factors such as old age, illness, or poor distinction between napping and sleepiness due to poor health.

Trichopoulos’ study focused on Greek participants in the European Prospective Investigation into Cancer and Nutrition, which enrolled participants between 1994 and 1999. The study included 28,571 volunteers aged 20 to 86 from all over Greece. After eliminating those with certain health conditions and other factors that made them inappropriate for the study, the study wound up with 23,681.

Participants reported whether they were taking midday naps and characterized them as either regular, three times a week for 30 or more minutes, or irregular, which would include those who napped once or twice a week for 30 or more minutes and those who napped more frequently but for less than a half an hour. They also collected data on the participants’ physical activity, diet, health, smoking status, age, education level, socioeconomic status and other factors.

By the end of the study period, 792 participants had died, 133 from coronary heart disease.

The results confirmed already known links between heart disease and factors such as smoking and obesity – which earlier studies have shown to increase the risk of dying from heart disease – and education, physical activity, and the Mediterranean diet, which have been shown to reduce the risk.

When other factors are controlled for, the study showed that taking an occasional nap lowers the risk of dying from heart disease by 12 percent, while regularly napping lowered the risk of dying from coronary heart disease by 37 percent.

Trichopoulos and his team broke the results down further, finding that working men got the greatest benefit, while there were not enough deaths of working women in the study to allow statistical analysis.

The study’s authors suggested that the results may reflect the effect of stress on a person’s health. Stress is a known factor contributing to heart disease, the authors said, and taking a nap may serve to relieve that.

Ironically, Trichopoulos said that even as the study shows the possible benefits of the traditional Greek work habits, uninterrupted, American-style workdays are becoming more prevalent there.

Trichopoulos said he’ll refrain from calling for sweeping changes to the way Americans conduct their work days until the results are confirmed by other studies. Until then, he said, a nap might help your heart health, so if you can, take one.

“I would not really advise major changes to work habits here without confirmation,” Trichopoulos said. “We know there’s no harm at all to a siesta and it’s actually enjoyable, so if you can, do it.”