A new study suggests that people who nap once or twice a week have a reduced risk of heart attack and stroke, however, more research is needed before napping can be recommended for good heart health.

We spend a third of our lives asleep and while we know the many benefits of a good night’s sleep for both our physical and mental health, what is less clear is the effects of napping on our cardiovascular health.

A new study published recently online in the British Medical Journal Heart suggests that people who nap once or twice a week had a lower risk of cardiovascular events such as a stroke or heart attack, compared to those who did not nap. However, the study did not find any link between this reduced risk and the frequency or length of naps.

According to the researchers of the study, the impact of napping on heart health has been hotly contested. Many of the published studies on the topic have failed to consider napping frequency, or focused purely on cardiovascular disease deaths, or compared regular nappers with those not opting for a mini siesta.

In a bid to try and address these issues, the researchers of this study looked at the link between napping frequency and average nap duration and the risk of fatal and non-fatal cardiovascular disease ‘events,’ such as heart attack, stroke, or heart failure, among 3,462 randomly selected people aged between 35 and 75 in Lausanne, Switzerland.

The participants’ first check-up took place between 2009 and 2012, when information on their sleep and nap patterns in the previous week was collected, and their health was then subsequently monitored for an average of five years.

Over half (58%, 2014) of the participants said they didn’t nap during the previous week; around one in five (19%, 667) said they took one to two naps; around one in 10 (12%, 411) said they took three to five; while a similar proportion (11%, 370) said they took six to seven naps.

Frequent nappers, those who took between 3 and 7 naps a week, tended to be older, male, smokers, weigh more, and to sleep for longer at night than those who said they didn’t nap during the day. These frequent nappers also reported more daytime sleepiness and more severe obstructive sleep apnoea–a condition in which the walls of the throat relax and narrow during sleep, interrupting normal breathing.

During the monitoring period, there were 155 fatal and non-fatal cardiovascular disease ‘events’ such as heart attack and stroke.

The findings suggested that occasional napping, once to twice a week, was associated with an almost halving in attack/stroke/heart failure risk (48%) compared with those who didn’t nap at all.

This association held true after taking account of potentially influential factors, such as age, and night-time sleep duration, as well as other cardiovascular disease risks, such as high blood pressure/cholesterol.

And it didn’t change after factoring in excessive daytime sleepiness, depression, and regularly sleeping for at least 6 hours a night. Only older age (65+) and severe sleep apnoea affected it.

However, the heightened cardiovascular risk initially observed for frequent nappers virtually disappeared after taking account of potentially influential factors. And no associations with cardiovascular disease ‘events’ were found for nap length (from 5 minutes to 1 hour plus).

This is an observational study, and as such, can’t establish cause, added to which the information on nap and sleep patterns relied on each participant in the study being able to remember their napping history. However, nap frequency may help to explain the differing conclusions reached by researchers about the impact of napping on heart health, suggested the study authors.

In a linked editorial, Drs Yue Leng and Kristine Yaffe, of the University of California at San Francisco, USA, pointed out that research in this area was hampered by the absence of a gold standard for defining and measuring naps, making it “premature to conclude on the appropriateness of napping for maintaining optimal heart health.”

“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,” they added.

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

Commenting Dr Angie Brown, Consultant Cardiologist and Medical Director of the Irish Heart Foundation said, “This study suggests that napping once or twice a week may be beneficial in reducing cardiovascular events. However, other studies on the risks and benefits of napping have been quite varied.”

“This research is an observational study so doesn’t give us any information about why this frequency of napping might be beneficial and the information on nap and sleep patterns also relied on personal recall rather than physiological measurements. Furthermore, it is difficult to compare studies as there is no gold standard for measuring and defining ‘naps’, making it difficult to make firm conclusions. However, the study is of interest and has promising results with potentially significant public health implications if the results can be confirmed and clarified.”

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(Heart 2019;0:1–6. doi:10.1136/heartjnl-2019-314999)