Abstract

Objective- To examine whether day napping or short night sleeping is associated with higher risk of diabetes.

Research design and methods- A prospective study of hours of daytime napping and night sleeping assessed in 1996-1997 in relation to diabetes diagnosed between 2000 and 2006 (n = 10,143) among 174,542 participants of the NIH-AARP Diet and Health Study. Odds ratios (OR) and 95% confidence intervals (CI) were derived from multivariate logistic regression models.

Results- Longer day napping was associated with higher risk of diabetes. After adjusting for potential confounders, compared with individuals who did not nap, the OR was 1.23 (95%CI: 1.18-1.29) for those reporting < 1 hour and 1.55 (95%CI: 1.45-1.66) for ≥ 1 hour of napping (P for trend < 0.0001). For night sleeping, with 7-8 hours as the referent, the OR was 1.46 (95%CI: 1.31-1.63) for < 5 hours, 1.11 (1.06-1.16) for 5-6 hours, and 1.11 (0.99-1.24) for ≥ 9 hours. In both analyses, additional adjustment for BMI only modestly attenuated the associations. Further analysis showed a statistically significant interaction between hours of napping and sleeping on diabetes (P for interaction < 0.0001). Among participants with no napping, only short night sleeping was associated with higher occurrence of diabetes, whereas among those with ≥ 1 hour of napping, both long and short sleeping was associated with higher risk.

Conclusions- Day napping and short night sleeping are associated with higher risk of diabetes. The association between sleep duration and diabetes may be modified by napping habit.