Background:Lack of sleep and increased consumption of energy-dense foods and sugar-sweetened beverages (SSB) have all been suggested as factors contributing to the increased prevalence of overweight and obesity.Objective:To evaluate whether objectively measured sleep duration (average and day-to-day variability) as well as parent-reported sleep problems are independently associated with proposed dietary risk factors for overweight and obesity in 8-11 year old children.Design:In this cross-sectional study data on sleep duration and day-to-day variability in sleep duration were measured in 676 Danish, apparently healthy children by an objective measure (actigraphy) for 8 nights, and the Children's Sleep Habits Questionnaire (CSHQ) was filled out by the parents. Diet was recorded using a web-based food record for 7 consecutive days. Fasting blood samples were obtained for measurements of plasma leptin and ghrelin levels.Results:Sleep duration (hours/night) was negatively and significantly (P0.003) associated with energy density (ED) of the diet (β=-0.32 kJ/g), added sugar (β=-1.50 E%) and SSB (β=-1.07 E%). Furthermore, variability in sleep duration (min/night) was positively associated with SSB (β=0.20 E%, P=0.03), independent of sleep duration, and CSHQ-score was positively associated with ED (β=0.16 kJ/g, P=0.04). All of these associations were independent of potential confounders (age, sex, pubertal status, height, weight, screen time, moderate-to-vigorous physical activity, and parental education and ethnicity).Conclusion:Our study suggests that short sleep duration, high sleep duration variability, and experiencing sleep problems are all associated with a poor, obesity-promoting diet in children.International Journal of Obesity accepted article preview online, 8 August 2013. doi:10.1038/ijo.2013.147.