Researchers found that siestas of 30 minutes or more in Murcia, a region of Spain, where it’s common to nap, were linked to a higher risk of obesity, a group of conditions called metabolic syndrome and high blood pressure.
“Not all siestas are the same. The length of time, position of sleep and other specific factors can affect the health outcomes of a nap,” said study co-author Marta Garaulet, a visiting professor in the division of sleep and circadian disorders at Brigham and Women's Hospital in Boston.
“A previous study that we conducted in a large study population in the U.K. had found that siestas were associated with an increased risk of obesity,” Garaulet said in a hospital news release. “We wanted to determine whether this would hold true in a country where siestas are more culturally embedded, in this case Spain, as well as how the length of time for siestas is related to metabolic health."
Investigators examined the relationship between daytime sleep and its duration with obesity and metabolic syndrome in more than 3,200 adults.
Folks who napped 30 minutes or longer were more likely to have a higher body mass index (BMI), higher blood pressure and a cluster of other conditions associated with heart disease and diabetes compared to those without siestas, the data showed.
People who took shorter "power naps” did not have these same increases in obesity and metabolic changes. They were also less likely to have elevated systolic blood pressure.
Compared with the no-siesta group, the long siesta group also had larger waists, and higher fasting blood sugar and blood pressure levels.
Long siestas were also associated with going to bed later and eating later at night. They were linked with eating more at lunch and with cigarette smoking.
Some of these factors may be a consequence of obesity and not siestas, the researchers noted.
They only found an association between napping and obesity, so cause and effect could not be established.
“This study shows the importance of considering siesta length and raises the question whether short naps may offer unique benefits. Many institutions are realizing the benefits of short naps, mostly for work productivity, but also increasingly for general health,” said co-author Frank Scheer, a senior neuroscientist and professor at Brigham.
Future studies are needed to further substantiate the advantages of shorter siestas, he said in the release.
Study results were published April 26 in Obesity.
The U.S. National Institutes of Health has more on metabolic syndrome.
SOURCE: Brigham and Women’s Hospital, news release, April 26, 2023