LAUSR

Cases of homicide allegedly committed during sleep have been described since ancient history. The strongest link between violence and sleep disorders is represented by the so-called parasomnias, a group of sleep disorders characterized by episodic undesirable behaviors and/or mental experiences that arise during sleep. We conducted a systematic search according to the PRISMA guidelines with 4 different search engines (Pubmed, Scopus, Embase and Cochrane) with the aim of gathering and critically evaluating all described cases of homicides associated with parasomnias We identified over 30 cases of homicide allegedly committed during a parasomnia episode. The diagnosis was of NREM sleep parasomnia for all cases except one, which received a diagnosis of REM-sleep behavior disorder (RBD). Victims were more often female family members, killed by firearms or sharp objects, usually nearby the bed. Aggressors often reported delusional/hallucinatory mental experiences associated with their episodes and rarely made any effort to cover up the crime. In the majority of the cases, no objective sleep data were available. Only a minority of patients had a positive childhood or family history. The court judgement was not uniform across cases. Although rarely, homicides could be committed during parasomnias episodes. Despite being more frequently associated with violent behaviors, RBD less likely led to fatal aggressions. According to the observed behaviors, subjective reports and current neurophysiological knowledge, patients are only partially conscious and largely disconnected from the external environment, and could not be considered guilty for their actions. None