Sleep duration and obesity in a population-based study.

Previous studies have demonstrated an association between sleep duration and obesity, but few population-based studies have examined the association. We examined the relationship between recent and usual lifetime sleep duration with the odds of obesity in 5549 women that participated in a population-based telephone survey. The structured telephone interview included questions on usual sleep duration in adult life and the recent past, as well as height and weight and other demographic and lifestyle characteristics. We examined odds of overweight (BMI: 25-29.9 kg/m(2)), obesity (BMI: 30-39.9 kg/m(2)) and extreme obesity (BMI: 40 kg/m(2)) according to reported sleep duration. Compared to women who slept 7-7.9h per night, women who slept an average of <6h per night in the recent past had significantly greater odds of obesity (Odds Ratio [OR]: 1.89; 95% Confidence Interval [CI]: 1.45-2.47) and extreme obesity (OR: 3.12; CI: 1.70-5.75), adjusting for potential confounding factors. Weaker associations were noted for short lifetime sleep duration. Current short sleep (<7h) was associated with greater odds of obesity (30 kg/m(2)) in those reporting less than 7h (OR: 1.59; 95% CI: 0.93-2.78) and in those reporting 8 or more hours (OR: 1.75; 95% CI: 1.33-2.32) of sleep throughout adult life. Current short sleepers were more likely to be obese regardless of their usual sleep duration earlier in life. These findings do not support the hypothesis that sleep duration is a causal factor in obesity.