Could grabbing a nap once or twice a week help you live longer?
A new study reports the occasional nap appears to cut in half people's risk of heart attack, strokes and heart disease, compared with folks who never nap.
But more frequent napping provided no benefit, researchers found.
"In fact, we found that frequent nappers had initially a higher risk for incident cardiovascular disease," said lead author Nadine Hausler, a postdoctoral researcher at University Hospital of Lausanne in Switzerland. "However, when we took sociodemographic, lifestyle and cardiovascular risk factors into account, this increased risk disappeared."
The findings left experts scratching their heads.
"I don't think it's anything definitive, in terms of whether napping is actually helpful or not helpful," said Marie-Pierre St-Onge, director of the sleep programme at Columbia University Irving Medical Center in New York City.
She noted that the health benefits of napping are a source of intense debate among researchers, with many arguing that naps are a sign of lousy nighttime sleep and, therefore, not a good thing.
"This throws a little bit of a curveball, because they found one to two naps per week might be beneficial," St-Onge said.
For this study, researchers looked at napping patterns of nearly 3 500 randomly selected people in Switzerland, and then tracked their heart health for more than five years.
About three in five said they don't nap. One in five said they nap once or twice a week - the same number who reported napping three or more days a week.
Frequent nappers tended to be older men with excess weight and a tobacco habit. Though they reported sleeping longer at night than those who don't nap, they also reported more daytime sleepiness and were more likely to have sleep apnea, a condition that wakes a person repeatedly in the night when their breathing stops.
During the five-year follow-up, participants had 155 fatal and non-fatal heart events, the findings showed. These could include heart attacks, strokes and heart disease caused by clogged arteries that required surgical reopening.
Napping once or twice a week cut a person's risk of heart attack, stroke and heart failure by 48%, compared with people who don't nap at all, the researchers found.
Frequent naps initially appeared to increase a person's heart risk by 67%, but that disappeared after accounting for other risk factors, the study authors noted.
Dr Martha Gulati, a cardiologist who is editor-in-chief of CardioSmart.org, the American College of Cardiology's patient website, said it makes sense that frequent napping could be a red flag for health problems.
"I worry that somebody that naps every day isn't getting good sleep," she said. "Somebody who takes six or seven naps a week, I ask, are you not sleeping well at night? Is that how you're catching up with your sleep?"
Gulati added, "But I am still going to enjoy my Sunday naps, and now say I am working on lowering my risk for heart disease when my husband asks."
Researcher Hausler couldn't say exactly why a couple of naps each week might do a body good.
"The mechanisms are not straightforward," she said. "We assume that occasional napping might be a result of a physiological compensation allowing to decrease the stress due to insufficient nocturnal sleep and, thus, could have a beneficial effect on cardiovascular disease events."
Though she said the results should first be confirmed by other studies, Hausler added: "We can say that an occasional nap can potentially decrease cardiovascular disease risk for healthy adults."
The study was published online September 9 in the journal Heart.
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