The relationship between sleep and obesity or weight gain in adults, particularly older populations, remains unclear. In a cohort of 83,377 US men and women aged 51-72 years, we prospectively investigated the association between self-reported sleep duration and weight change over an average of 7.5 years of follow-up (1995-2004). Participants were free of cancer, heart disease, and stroke at baseline and throughout the follow-up. We observed an inverse association between sleep duration per night and weight gain in both men (P for trend = 0.02) and women (P for trend < 0.001). Compared with 7-8 hours of sleep, shorter sleep (<5 hours or 5-6 hours) was associated with more weight gain (in kilograms; men: for <5 hours, β = 0.66, 95% confidence interval (CI): 0.19, 1.13, and for 5-6 hours, β = 0.12, 95% CI: -0.02, 0.26; women: for <5 hours, β = 0.43, 95% CI: 0.00, 0.86, and for 5-6 hours, β = 0.23, 95% CI: 0.08, 0.37). Among men and women who were not obese at baseline, participants who reported less than 5 hours of sleep per night had an approximately 40% higher risk of developing obesity than did those who reported 7-8 hours of sleep (for men, odds ratio = 1.45, 95% CI: 1.06, 1.99; for women, odds ratio = 1.37, 95% CI: 1.04, 1.79). The association between short sleep and excess weight gain was generally consistent across different categories of age, educational level, smoking status, baseline body mass index, and physical activity level.
Keywords: body mass index; obesity; sleep.