Researchers from the University Hospital of Lausanne, Switzerland studied the association between napping frequency and duration and the risk of fatal and non-fatal cardiovascular disease
Tracking 3,462 people between the ages of 35 and 75 for just over five years, the report authors found that those who indulged in occasional napping -- once or twice a week, for between five minutes to an hour -- were 48% less likely to suffer a heart attack, stroke
or heart failure than those who did not nap at all.
The observational study, which was published in Heart
, the journal of the British Cardiovascular Society, found that no such association emerged for greater frequency or duration of naps.
While some studies have been done on the impact of napping on heart health, many published studies fail to consider napping frequency or duration, the researchers said.
"Subjects who nap once or twice per week have a lower risk of incident CVD (cardiovascular disease) events, while no association was found for more frequent napping or napping duration," the report authors said.
"Sleep patterns have previously been reported to be associated with a range of chronic medical conditions," said Stephen MacMahon, a cardiovascular expert at Oxford University's George Institute for Global Health, who was not involved in the study.
"Some, but not all, these associations will reflect the effects of underlying chronic disease on sleep rather than the converse. It's often difficult to untangle what is cause and effect, especially when some serious conditions, such as coronary heart disease, can be largely symptom-free for decades prior to a critical complication such as a heart attack," he told the Science Media Centre (SMC) in London.
Naveed Sattar, Professor of Metabolic Medicine at the University of Glasgow, said that while the study was "somewhat interesting", it seems that those who nap once or twice a week have healthier or organized lifestyles, but that those who napped daily were likely to be more sick.
"This means the former pattern of occasional napping is intentional and the latter of more regular napping likely represents sub-clinical illness linked to poorer lifestyle. This would then explain the differential risks," Sattar told the SMC.
"I don't think one can work out from this work whether "intentional" napping on one or two days per week improves heart health so no one should take from this that napping is a way to lessen their heart attack risk," he added.
"For now, far better to aim for regular good night's sleep and to follow usual lifestyle advice of good diets and decent activity levels."