"Sleep sex," also known as sexsomnia, is a sleep disorder characterized by sexual behaviors committed while asleep. There has recently been increased interest in sexsomnia due to controversies arising in legal trials that have been widely publicized in the social and public media. This article attempts to marshal the current information about sexsomnia from the forensic literature and provides an overview of sexsomnia including common features, precipitating factors, prevalence rates, diagnostic procedures, and treatment. As sexsomnia represents a condition in which sexual acts are committed without awareness or intention, this paper also reviews the development of sexsomnia as a legal defense and summarizes Canadian case law on the topic. It provides an overview of the hurdles presented to defense attorneys attempting to utilize the defense and examines popular public notions surrounding the legitimacy of sexsomnia and the possibility of malingering. We conclude that sexsomnia is a legitimate sleep disorder for which case law now exists to support its use in legal defenses based on automatism. The question of whether it is an example of "sane" or "insane" automatism remains to be determined by the courts. Regardless of whether or not sexsomnia is determined to be a mental disorder by the courts, it is now a recognized and well-described sleep disorder that can be safely treated and managed by knowledgeable clinicians.