Childhood obesity continues to be a major public health concern in the United States. This work reviews the current understanding of the relationship between sleep duration and obesity among children and adolescents. A systematic search was conducted for papers published between January 2000 and July 2013 using keywords: (sleep) and (overweight or obesity or obese or body mass index or BMI or adiposity or body fat or fat) and (children or child or youth or teen or pediatric or adolescent or paediatric or childhood or adolescence or boy or girl). Reference lists of relevant articles and reviews or meta-analysis articles were checked to identify additional studies. Only empirical work and longitudinal studies that focused on children and adolescents were included in this review. The search identified 22 longitudinal studies. The majority of the reviewed studies support the presence of an inverse relationship between sleep duration and obesity. However, in some studies the relationship was not significant in adjusted analyses. Differences as a function of age and gender were also noted. Despite more than a decade of research, the debate on the association between sleep duration and obesity continues. Further research with repeated assessments, valid objective measures, and better control of potential confounding variables is warranted.