Violent behaviors during sleep. Violent behaviors during sleep are probably underdiagnosed but frequent and disabling complaints. They refer to behaviors ranging from simple dream enactment to complex behaviors that may have serious or even lethal consequences for oneself or other individuals. After awakening, the subjects are often unaware of their actions and had partial or complete amnesia of the episode. The violent behaviors during sleep may have multiple aetiologies. The parasomnias, including the disorders of arousal and the rapid eye movement sleep behavior disorder are mainly involved. A carefully clinical interview may help the clinician to rule out the differential diagnoses (i.e. nocturnal frontal lobe epilepsy, sleep related dissociative disorder) and to address the patient for further investigations. This article provides a brief overview of the epidemiology, the diagnosis, the prognosis and the treatment of the main causes of violent behaviors during sleep.