Sleep and Obesity. Are there gender or race differences? The Adventist Health Study 2

Objective: The obesity epidemic and its association with chronic diseases is a major public health concern. Modifiable factors such as sleep duration have been associated with obesity. However, further clarification is needed in determining possible gender and racial differences. Methods: Cross-sectional study of 56390 subjects (mean age 58 years, 63% female, 77% white) from the Adventist Health Study 2. Sleep duration was categorized in hours (hrs) of sleep with 8hrs set as reference. Logistic regression was used in the analysis with BMI >24.9 defined as overweight/obese. Adjustments were made for age, physical activity, dietary energy intake, income, education, smoking, alcohol intake, medication and other relevant factors. Results: Odds ratios for being overweight/obese were significantly different between the sexes and races (p<0.05). A significant interaction was found between sex and sleep duration (p<0.05) but not between race and sleep duration. In men sleeping less, tended to be more strongly related to obesity than in women. In men: <5 hrs: OR=1.85, (95% CI 1.47-2.32); 5 hrs: OR=1.56, (95% CI 1.36-1.78); 6 hrs: OR=1.30, (95% CI 1.19-1.42); 7 hrs: OR=1.10, (95% CI 1.02-1.18) vs. in women: < 5 hrs: OR=1.70, (95% CI 1.45-1.99); 5 hrs: OR=1.37, (95% CI 1.24-1.50); 6 hrs: OR=1.21, (95% CI 1.13-1.29); 7 hrs: OR=1. Conclusions: No significant interactions were observed in the association between sleep and obesity in blacks and whites. Shorter sleep duration was more strongly correlated to obesity in men than in women. Gender differences will need further exploration and additional research is warranted before recommending alterations in sleep behaviour.