This is the main takeaway of an observational study appearing in the BMJ journal Heart.
Nadine Häusler, Ph.D., from the department of internal medicine at Lausanne University Hospital, in Switzerland, is the first author of the study.
As Häusler and colleagues explain in their paper, much controversy has surrounded the relationship between daytime napping and cardiovascular health.
Some previous studies, referenced by the authors, have found a lower risk of coronary heart disease among daytime nappers, while others have found a higher risk of cardiac events or cardiovascular mortality among those who regularly nap during the day.
To help settle the controversy, Häusler and the team set out to examine the link between napping and fatal and nonfatal cardiovascular events in a cohort of 3,462 adults in Switzerland.
Studying naps and cardiovascular events
Häusler and colleagues had access to medical data from participants in the CoLaus cohort study.
The participants were between 35 and 75 years of age when they enrolled in the CoLaus study and did not have a history of cardiovascular problems at baseline, that is, in 2003–2006.
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.
When the participants were asked about their sleeping and napping patterns, more than half reported no naps in the previous week, almost 20% said they had napped once or twice, about 12% said they had napped 3–5 times, and a similar number said they had napped 6–7 times.
Those who napped more frequently tended to be older, overweight males who smoked. These participants also tended to sleep for longer at night, have sleep apnea, and feel more sleepy during the day.