According to researchers at Harvard and the University of Athens Medical School, regular naps are good for the heart.

After conducting a six-year study of nearly 24,000 Greek adults, the researchers found that those who took midday naps on a regular basis, lowered their risk of dying from heart disease by more than a third.

They say people who made a habit of napping at least three times a week for a minimum of 30 minutes had a 37 percent lower risk of dying from heart disease compared to non-nappers.

The researchers say the relationship was even stronger among employed men as compared to unemployed men, as the naps appeared to relieve work-related stress which is bad for hearts.

The same conclusion could not be made for working women because of a limited number of subjects.

Lead author Androniki Naska says their findings suggest that for healthy adults a siesta has an impact on stress and may reduce coronary mortality.

Naska says the siesta habit is common in many parts of the world, including the Mediterranean region and Central America, and they found that even occasional nappers were less likely to die from heart problems than those who did not nap.

The study of 23,681 Greek men and women found strong evidence in support of the siesta.

Out of 792 men and women who died during the follow-up period, 133 died from heart disease.

Their ages ranged from 20 to 86 and had no history of heart disease or any other severe condition when the study began; they were monitored for an average of 6.32 years.

Siestas produced a 36 per cent reduction in heart disease death risk for non-working men.

Among working men, napping of any sort resulted in a 64 per cent reduced risk of heart disease death.

A similar analysis of working and non-working women was not possible because only six deaths occurred among working women.

Previous studies that have produced mixed findings on the heart benefits of napping, however this study was based on people who died from heart problems, rather than on those who survived and would be more likely to nap.

Senior author, Dimitrios Trichopoulos of the Harvard School of Public Health, says if the results are valid and were to be confirmed, the benefit of naps would be comparable to the benefits of the Mediterranean diet, the effects of which are proven.

Trichopoulos says the so-called waking effect factor is also a consideration where the risk of heart attack rises in the morning possibly because awakening suddenly, triggers a surge in hormone secretions and blood pressure.

It was not known if waking suddenly from a nap posed a similar risk, but Trichopoulos says those who have been taking naps should continue to do so.

The study is published in the Archives of Internal Medicine.