The relationship between attention-deficit/hyperactivity disorder (ADHD) and sleep is a complex one which poses many challenges in clinical practice. Studies of sleep disturbances in children with academic and behavioral problems have underscored the role that primary sleep disorders play in the clinical presentation of symptoms of inattention and behavioral dysregulation. In addition, recent research has shed further light on the prevalence, type, risk factors for, and impact of sleep disturbances in children with ADHD. The following discussion of the multi-level and bi-directional relationships among sleep, neurobehavioral functioning, and the clinical syndrome of ADHD synthesizes current knowledge about the interaction of sleep and attention/arousal in these children. Guidelines are provided, outlining a clinical approach to evaluation and management of children with ADHD and sleep problems.