Sleep, Naps and Diabetes Risk

If a siesta is part of your everyday routine, there may be cause for concern.

A new study from Japan found that daytime sleepiness and regularly taking long daytime naps may be linked to an increased risk of type 2 diabetes.

Type 2 diabetes is a chronic condition that affects the way the body processes blood sugar. Diabetes greatly increase a patient's risk of serious complications, such as heart disease, stroke and kidney failure.

A team of researchers led by Tomohide Yamada, MD, PhD, a specialist in diabetes research at the University of Tokyo, compared the findings of multiple studies on the topic. Out of 683 articles, these researchers selected 10 for this study. These articles included 261,365 patients from the US, China, Sweden, Spain and Finland.

Excessive daytime sleepiness was tied to a 56 percent increased risk of type 2 diabetes. Daytime naps also appeared to increase this risk, with longer naps linked to greater risk.

A nap that lasted 40 minutes or less per day was not linked to an increased risk of diabetes. However, a nap that lasted between 40 and 60 minutes per day sharply increased this risk. A nap that lasted 60 minutes or more per day increased the risk of diabetes by 46 percent compared to patients who didn't nap.

According to Dr. Yamada and team, a healthy sleep cycle supports overall physical health in combination with a healthy diet and exercise. But excessive daytime sleepiness and napping can signal a problem.

“Daytime napping might be a consequence of night-time sleep disturbance such as obstructive sleep apnea (OSA),” Dr. Yamada and colleagues wrote. “Previous research has shown that sleep apnea affects blood sugar and may increase the risk of type 2 diabetes.”

This study was presented Sept. 17 at the annual meeting of the European Association for the Study of Diabetes. Research presented at conferences may not have been peer-reviewed.

No funding sources or conflicts of interest were disclosed.