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With World Heart Day set to be observed next week, our concierge family doctors at MD 2.0 in Jupiter want to draw your attention to a new study about the part twice-weekly naps can play in improving heart health.

Created by the World Heart Federation, World Heart Day is celebrated every September 29th to inform people around the globe that cardiovascular disease (CVD) is the leading cause of death, claiming 17.9 million lives every year, and to highlight the actions individuals can take to prevent and control CVD.

A new study, published this month in the BMJ journal Heart, suggests that one of those actions might include napping once or twice a week.

The study

Over five years, researchers in Switzerland collected data from nearly 3,500 Swiss adults ages 35 to 75. They found that those who napped once or twice a week had a 48 percent lower risk for heart attacks, strokes, or heart failure than those who never took naps. This benefit did not appear to increase for those who napped more often, and nap length did not make a difference: Anything from five minutes to an hour produced a significant result.

Researchers couldn’t say for sure what accounted for the increased benefit of occasional naps. Lead study author Nadine Hausler, a postdoctoral researcher at University Hospital of Lausanne in Switzerland, admitted as much in a statement released along with the study.

“The mechanisms are not straightforward,” she said. “We assume that occasional napping might be a result of a physiological compensation allowing [the body] to decrease the stress due to insufficient nocturnal sleep, and thus, could have a beneficial effect on cardiovascular disease events.”

Another explanation could be that sleep is the time the body uses to repair itself. When we’re sleeping, the body lowers cortisol and repairs the damage to cells inflicted during the day. Japanese researchers found that losing six hours of sleep over a single night resulted in significantly elevated blood glucose and triglyceride levels, warning signs for increased risk of heart disease and diabetes. Naps can help make up that deficiency.

Earlier studies, similar results

A large, six-year study in 2007 likewise showed a marked benefit to napping. In that study, researchers tracked the napping habits of nearly 24,000 healthy Greek adults. They found that, even after accounting for such unhealthy practices as smoking and poor diet, participants who napped for a half-hour three times a week had a 37 percent lower risk of dying from CVD than those who didn’t.

Another study in 2015 found that a 30-minute nap restored neuroendocrine and immune biomarkers to normal levels in those who hadn’t slept well the night before. (Biomarkers are signs in molecules indicating health or disease in the body.)

The effects of napping have been controversial since several studies in the past few years have shown an increase in CVD in those who napped frequently and for lengthy periods during the day. But several experts explained those findings were likely due to the cohort studied. That is, the participants were older than 65 and in ill health, and that excessive napping in their case may a symptom, rather than a cause of cardiac events.

Nap hygiene

People all over the world take naps regularly. Mediterranean countries even build the famous siesta into the culture. Scientists have found that among these populations—who also consume a heart-healthy diet—longevity is greater than here in the U.S. Humans are hard-wired to nap in the afternoon, when core body temperature dips as part of the natural circadian rhythm.

In this country, however, where “productivity” is king, napping is often seen as a sign of laziness, especially among younger people. But prior research has shown that the so-called “power nap” of up to 20 minutes helps boost alertness and mood and improve motor performance, thus actually increasing productivity.

So what’s the best way to go about taking a restorative nap?

1. The optimal time for a nap is between 1 p.m. and 3 p.m. Napping any later than this can leave you sleepless at bedtime.

2. Aim for 20 minutes. Longer naps can leave you feeling groggy and disoriented for some time afterward.

3. Give yourself a few minutes after waking to resume demanding activities, especially those that require alertness.

And if you’ve been feeling as if you need more naps than normally, or are having trouble falling or staying asleep at night, be sure to talk to us. This could signal either a problem with medication you’re taking or a health issue that needs to be addressed.