Study: Napping for more than 30 minutes linked to obesity, high blood pressure

BOSTON — Napping during the middle of the day has the potential to affect sleep quality, cognitive function, and metabolic processes, according to a new study.

Researchers at Brigham and Women’s Hospital found that people who take midday naps had higher body mass indexes and were more likely to have metabolic syndrome than those who did not take siestas, according to results published in Obesity.

The hospital says it analyzed more than 3,000 adults from a Mediterranean population, examining the relationship of siestas and siesta duration with obesity and metabolic syndrome.

Data from the findings showed that those who took naps of 30 minutes or longer were more likely to have a higher body mass index, higher blood pressure, and a cluster of other conditions associated with heart disease and diabetes compared to those without siestas, researchers said.

“Not all siestas are the same. The length of time, the position of sleep, and other specific factors can affect the health outcomes of a nap,” said senior author Marta Garaulet, PhD, a visiting professor in the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital. “A previous study that we conducted in a large study population in the UK found that siestas were associated with an increased risk of obesity. 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.”

In contrast, short nap-takers were less likely to have elevated systolic blood pressure than those who took no siestas.

The researchers also found that long naps were associated with later nightly sleep timing and food timing, with increased energy intake at lunch and cigarette smoking, and with the location of siestas (a bed vs. a sofa), which may explain the higher risks associated with longer duration siestas.

“This study shows the importance of considering siesta length and raises the question of 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, PhD, a senior neuroscientist and professor in the Medical Chronobiology Program in the Brigham’s Division of Sleep and Circadian Disorders.

The word siesta comes from the Latin base “sexta,” which means sixth and refers to the sixth hour, or “sexta hora,” of daylight.

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