Obesity causes or exacerbates a host of medical conditions, including cardiovascular, pulmonary, and endocrine diseases. In addition, there is growing evidence that obesity and sleep problems are linked in adolescents and that they are significant obstacles for learning, having a negative impact on behavior, and attainment of social competence and quality of life. The theoretical basis of this relationship is discussed. Several studies investigating the relationships between obesity, sleep disturbance, and a number of important negative outcomes are reviewed.