Poor sleep has increasingly gained attention as a contributor to the obesity epidemic. The increased prevalence of obesity in Western nations over the past half-century has been paralleled by a severe reduction in sleep duration. Physiological studies suggest reduced sleep may impact hormonal regulation of appetite. Prospective studies suggest reduced habitual sleep duration as assessed by self-report is a risk factor for an increased rate of weight gain and obesity.Thus, reduced sleep appears to represent a independent risk factor for increased weight gain. Further research is required to determine whether interventions aimed at increasing sleep may be useful in combating obesity.