Day Napping and Short Night Sleeping Are Associated With Higher Risk of Diabetes in Older Adults

OBJECTIVE: To examine whether day napping or short night sleeping is associated with higher risk of diabetes. RESEARCH DESIGN AND METHODS: 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. RESULTS: 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 ≥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 ≥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 ≥1 h 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.