The “siesta” or daytime nap common in tropical Mexico, South America and countries bordering the warm Mediterranean Sea has again been put forward as beneficial to heart health.

Previous clinical studies have associated the siesta habit with a 37 percent reduction in coronary mortality. Doctors said this might be due to reduced cardiovascular stress mediated by daytime sleep. It’s also been found hour-long naps might boost mental ability for the elderly.

The mystery of the siesta is that it’s still not known if this daytime nap itself, a supine posture or the expectancy of a nap is the most important factor triggering its health benefits.

There are also conflicting conclusions about the relationship between cardiovascular health and taking a siesta. To add to the confusion, some studies have found a lower risk of coronary heart disease (CHD) among daytime nappers. Others have found a higher risk of cardiac events or cardiovascular mortality among those who regularly nap during the day.

Now, a new observational study appearing in the BMJ journal, Heart, found that taking a siesta or daytime nap once or twice a week might halve the risk of cardiovascular events such as heart attacks, strokes and heart failure.

Nadine Häusler, PhD, from the department of internal medicine at Lausanne University Hospital in Switzerland, and a team of researchers examined the link between napping and fatal and nonfatal cardiovascular events among 3,462 adults in Switzerland.

Participants were between 35 and 75 years of age when they enrolled in the CoLaus study. They did not have a history of cardiovascular problems at baseline, which was from 2003 to 2006.

On the one hand, researchers looked at the associations between napping frequency and napping duration and the incidence of heart attacks, strokes and heart failure on the other.

Häusler and the team had access to self-reported sleeping patterns and continual health monitoring over an average period of 5 years as part of the CoLaus study.

Participants were asked about their sleeping and napping patterns. More than half reported no naps in the previous week. About 20 percent said they had napped once or twice. Some 12 percent said they had napped 3 to 5 times, while a similar number said they had napped 6 to 7 times.

Those that napped more frequently tended to be older, overweight males who smoke. These participants also tended to sleep for longer at night, have sleep apnea and feel sleepier during the day.

There were 155 cardiovascular events during the 5-year monitoring period. Researchers accounted for potential confounders such as age or heart disease risk factors, such as hypertension, when assessing the association between naps and cardiovascular events.

Researchers found that taking one to two weekly naps during the day was linked with 48 percent lower chances of having a heart attack, stroke or heart failure compared with those who did not nap at all.

The analysis revealed no link between cardiovascular events and the duration of the naps.

"Subjects who nap once or twice per week have a lower risk of incident [cardiovascular disease] events, while no association was found for more frequent napping or napping duration,” the study said.

"Nap frequency may help explain the discrepant findings regarding the association between napping and [cardiovascular disease] events."

Napping can lower blood pressure and prevent future heart attacks, new research has found. epSos .de CC BY 2.0