Sleep Duration and Daytime Napping and Risk of Type 2 Diabetes among Japanese Men and Women: the Japan Collaborative Cohort Study for Evaluation of Cancer Risk.

Abstract

BackgroundLittle is known about the impacts of sleep duration and daytime napping on the risk of type 2 diabetes mellitus (T2DM).MethodsIn this study, 20,318 participants (7,597 men, 12,721 women) aged 40-79 years without a history of T2DM, stroke, coronary heart disease, or cancer at baseline (1988-1990), completed the baseline survey and the 5-year follow-up questionnaires, which included average sleep duration, napping habits, and self-reports of physician-diagnosed diabetes. The multivariable odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a logistic regression model.ResultsDuring the 5-year follow-up, 531 new cases of T2DM (266 men and 265 women) were documented. Sleep duration ≥ 10 h was associated with higher risk of T2DM compared to sleep duration of 7 h (OR 1.99: 95%CI, 1.28-3.08). The excess risk was observed for both sexes and primarily found among the non-overweight; the multivariable ORs of sleeping ≥ 10 h compared to 7 h were 2.05 (1.26-3.35) for the non-overweight (BMI < 25 kg/m2) and 1.38 (0.49-3.83) for the overweight (BMI ≥ 25 kg/m2). The respective ORs of nappers vs non-nappers were 1.30 (1.03-1.63) and 0.92 (0.65-1.29). Among the non-overweight, nappers who slept ≥ 10 h had the highest risk of T2DM (OR 2.84: 95%CI, 1.57-5.14), non-nappers who slept ≥ 10 h (2.27: 1.27-4.06), and nappers who slept < 10 h (1.30: 1.03-1.64), compared with non-nappers who slept < 10 h.ConclusionsLong sleep duration was associated with the risk of T2DM in both sexes, which was confined to the non-overweight.