A daytime nap once or twice a week can help lower the risk of having a heart attack or stroke, a new study found. So far, the findings are observational — they shouldn’t be used to infer a cause-effect relationship.

A paper looking at the association between napping frequency, average nap duration, and the risk of (both fatal and non-fatal) cardiovascular events found that taking as few as one or two naps a week can help reduce the risk of having a heart attack, stroke, or heart failure. However, no such link was established for greater frequency or duration of naps.

Hearty naps

“The study of napping is a challenging but also a promising field with potentially significant public health implications,” the authors explain. “While there remain more questions than answers, it is time to start unveiling the power of naps for a supercharged heart.”

Whether or not napping brings any health benefits to the table is still an ongoing debate. The authors explain that past research into the issue hasn’t taken napping frequency into account, focused purely on cardiovascular disease deaths, or compared regular nappers with those who don’t nap. All of this left us with a skewed perception of the benefits of napping.

In an effort to guide this debate, the team analyzed the association between napping frequency, average nap duration, and the risk of fatal and non-fatal cardiovascular disease ‘events,’ such as heart attack, stroke, or heart failure, among 3462 randomly selected residents of Lausanne, Switzerland. The participants were between 35 and 75 years old (when recruited for the study, between 2003 and 2006).

Each participant had a check-up sometime between 2009 and 2012 when the team recorded information on their sleep and nap patterns in the previous week. Their health was then subsequently monitored for an average of 5 years.

Over half of the participants (58%) said that they didn’t nap in the previous week, 19% said they took one to two naps, 12% reported taking between three and five, while a very-well-rested 11% said they took between six and seven naps in the previous week. The most frequent nappers (3-7 per week) tended to be older, male, smokers, and tended to weigh more and sleep for longer at night than non-nappers. They also reported more daytime sleepiness and more severe obstructive sleep apnea — a condition in which the walls of the throat relax and narrow during sleep, interrupting normal breathing.

The team recorded 155 fatal and non-fatal cardiovascular disease ‘events’ over the study period.

Occasional napping (1-2 per week) was associated with a 48% lower risk of a heart attack, stroke, or heart failure compared with those who didn’t nap at all. This association held true even after controlling for factors such as age, nighttime sleep duration, daytime sleepiness, depression, and regularity of sleep, as well as other cardiovascular disease risks, such as high blood pressure/cholesterol.

The only factors that influenced this link were older age (65+) and severe sleep apnea.

Frequent nappers initially showed a 67% heightened cardiovascular risk, but this disappeared after taking account of potentially influential factors. The team further reports finding no associations with cardiovascular disease ‘events’ for nap length (from 5 minutes to 1 hour plus).

The study relied on personally-reported information and shouldn’t be used to establish a cause-effect relationship, the team explains. However, they add that nap frequency may help to explain the differing conclusions reached by researchers about the impact of napping on heart health in previous studies. Research in this area is further hampered by the absence of a clear standard for defining and measuring naps.

“While the exact physiological pathways linking daytime napping to [cardiovascular disease] risk is not clear, [this research] contributes to the ongoing debate on the health implications of napping, and suggests that it might not only be the duration, but also the frequency that matters,” the study concludes.

The paper “Association of napping with incident cardiovascular events in a prospective cohort study” has been published in the journal Heart.