Day napping and short night sleeping are associated with higher risk of diabetes in older adults

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

This was a prospective study of hours of day napping and night sleeping assessed in 1996-1997 in relation to diabetes diagnosed between 2000 and 2006 (n = 10,143) among 174,542 participants in the National Institutes of Health (NIH)-AARP Diet and Health Study. Odds ratios (ORs) and 95% CI were derived from multivariate logistic regression models.

Longer day napping was associated with a higher risk of diabetes. After adjustment for potential confounders, ORs were 1.23 (95% CI 1.18-1.29) for those reporting <1 h and 1.55 (95% CI 1.45-1.66) for those reporting > or =1 h of napping compared with individuals who did not nap (P(trend) < 0.0001). For night sleeping, with 7-8 h as the referent, the OR was 1.46 (95% CI 1.31-1.63) for <5 h, 1.11 (1.06-1.16) for 5-6 h, and 1.11 (0.99-1.24) for > or =9 h. 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(interaction) < 0.0001). Among participants with no napping, only short night sleeping was associated with higher occurrence of diabetes, whereas among those with > or =1 h of napping, both long and short sleeping was associated with higher risk.

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.