Sleep-related violence in parasomnias: Forensic and clinical insights for criminal responsibility assessments

Parasomnias are undesirable physical events during sleep that can manifest as complex, violent behaviors, posing significant challenges for forensic psychiatry. The central legal dilemma involves "automatism," where actions lack the necessary mens rea for criminal liability. This study analyzes the prevalence, clinical characteristics, and adjudication of parasomnia defences within the Turkish legal system.

A retrospective analysis was conducted using the nationwide archives of the Council of Forensic Medicine through the National Judicial Network Project database over a five-year period. Criminal cases explicitly raising a parasomnia defence were identified and evaluated by a multidisciplinary board under the legal framework of "temporary causes" (Article 34) of the Turkish Penal Code.

Among 8920 criminal responsibility case files evaluated during the study period, a UYAP-based search and stepwise screening process identified 42 files with a documented parasomnia diagnosis or provisional diagnosis, of which 18 explicitly involved a parasomnia/sleepwalking defence. The multidisciplinary evaluation concluded that 4 subjects (22.2%) lacked criminal responsibility due to genuine sleep automatism. These validated cases involved violence against family members and were characterized by amnesia, confusion upon awakening, and lack of motive. Conversely, 14 defences were rejected, primarily due to exclusionary factors such as alcohol/substance intoxication (50%) or evidence of complex, goal-directed behavior inconsistent with parasomnia.

While sleep-related violence is a rare forensic entity, it presents significant diagnostic and legal challenges. This study underscores that in Continental Law jurisdictions like Türkiye, such cases are adjudicated as 'temporary causes' through a rigorous multidisciplinary lens. The implementation of a structured evidentiary framework for medico-legal triangulation-integrating clinical history, event phenomenology, and objective sleep data-is essential to foster transparency and objectivity in criminal responsibility assessments, effectively differentiating genuine sleep automatism from volitional conduct, malingering, or intoxication-related behaviors.