The average sleep duration of men and women in the JHS is less than the recommended amount. The findings from this study depict a significant negative relationship between sleep duration and body composition (BMI and WC) in men, which is in contrast to findings from the Cardia Study,
14 which examined gender differences in sleep duration and body composition in whites and African Americans and concluded that sleep duration may have a greater influence on women's body composition than men's. In addition, the Sleep and Health in Women study
15 assessed the sleep duration, sleep stages, and central obesity in women and found significant negative associations between sleep duration and central obesity after adjusting for BMI. The current study did not find any relationship between sleep duration and body composition in women. The Nurses’ Health Study,
16 a cohort of married, middle-aged women in the nursing profession, found that over a 16-year period, women who slept 5 hours or less gained 1.14 kg. They also found that women who slept 6 hours gained 0.71 kg more than women who slept 7 hours. Meyer et al
17 found the prevalence of overweight (BMI, ≥25) and obesity (BMI, ≥30) among men to be inversely associated with sleep duration and a positive, statistically significant association in women between mean BMI and trouble falling or staying asleep. Park et al
18 also found the inverse log relationship in men between sleep and general obesity. A population-based study that examined the relationship between recent and lifetime sleep in women via a telephone interview determined that women who were obese (BMI, 30-39.9 kg/m
2) and severely obese (BMI, ≥40 kg/m
2) were more likely to report shorter sleep durations in the recent past and over their lifetime.
9 In a Chinese population, persons who were overweight and obese as defined by the Ministry of Health and Welfare in Taiwan had an increased risk of 40% to 60%, respectively, of being poor sleepers.
19 Reportedly, African Americans have more short and long sleep durations.
4,20 Furthermore, sleep duration has been shown to mitigate the risk of symptoms of cardiovascular disease, type 2 diabetes mellitus, and high blood pressure in African Americans.
4,21,22