To review the state-dependent nature of violence and present a clinically useful classification of sleep violence, this article reviews our experience with sleep-related violence, establishing a differential diagnosis, methods of evaluation, and treatment options. The study occurs in a full-service clinical sleep disorders center evaluating approximately 1000 patients annually with an active participation of 16 physicians representing seven specialties. The patients were self-, physician-, or court/social service-referred for evaluation of violent or injurious behaviors associated with the sleep period. Interventions were dependent on the final diagnosis following clinical and (usually) sleep laboratory evaluation. The main outcome measures were self-reported. During routine clinical evaluations at a multidisciplinary sleep disorder center, it has become apparent that violence is often state-dependent, occurring only during the sleep period, resulting from a number of both neurologic and psychiatric conditions (including malingering and Munchausen syndrome by proxy). In such cases, careful clinical and laboratory evaluation usually results in a specific diagnosis, with effective therapeutic recommendations. Violence may be state-dependent. It is clear that violent behaviors may arise from the sleep period, often without conscious awareness on the part of the subject. This has social, forensic, and clinical implications, and may help contribute to the understanding of violence in general.