Why you shouldn’t nap for more than 40 minutes - it could harm your health
Diabetes expert says short naps may be good for us but longer siestas are definitely bad for us, being associated with increased risk of suffering high blood pressure and other conditions
Taking long naps or being excessively tired during the day is associated with a higher risk for developing metabolic syndrome, according to a new study by University of Tokyo researchers. Specifically, napping for 40 minutes or longer was associated with a steep increase in the risk of developing metabolic syndrome – a collection of health conditions such as high blood pressure, high cholesterol, excess fat around the waist and high blood sugar that all increase a person’s risk for heart disease.
The research team, led by diabetologist Dr Tomohide Yamada, evaluated data from 21 observational studies involving 307,237 Asian and Western subjects. Participants reported their daytime sleepiness and napping habits through a questionnaire, and their responses were compared to their history of metabolic syndrome, type-2 diabetes and obesity. The results showed a J-shaped relationship between time spent napping and metabolic syndrome risk.
Subjects who napped for less than 40 minutes did not show any increased risk for metabolic syndrome, but beyond 40 minutes, risk sharply rose. Napping for 90 minutes appeared to increase metabolic syndrome risk by as much as 50 per cent, as did being excessively tired during the day. Interestingly, there was a slight dip or decrease in the risk of metabolic syndrome among those napping less than 30 minutes.
“Sleep is an important component of our healthy lifestyle, as well as diet and exercise,” Yamada says. “Short naps might have a beneficial effect on our health, but we don’t yet know the strength of that effect or the mechanism by which it works.”
