"Befogging reason, undermining will: Understanding the prohibition of sleep deprivation as torture and ill-treatment in international law.

Background: Sleep deprivation is a prevalent method of psychological torture. However, difficulties in documentation have meant that it is not adequately appreciated by courts and other quasijudicial institutions such as UN treaty bodies.

Method: This paper aims to review the legal literature on deprivation of sleep, the definition, and prohibition of torture and ill-treatment, and its health impacts. A number of texts were identified and analyzed based on contextual relevance: criminal justice processes as well as medical literature on health impacts. The texts were identified via a search of key legal and health databases using the search terms "sleep deprivation," "sleep adjustment," and "sleep regulation." These texts were limited to English-language journal articles, NGO reports, court-cases and UN documents since 1950. They were then analyzed for their approaches to conceptualizing sleep deprivation from the perspective of assessing "severe pain and suffering" and the "diminishment of mental capacity".

Results/discussion: Sleep deprivation is an ill-defined and, in turn, poorly documented method of torture, particularly when prolonged or inflicted in combination with other methods (e.g., threats) and conditions (e.g., disruptive environment or time of day). More nuanced legal principles, informed by medical evidence, are lacking. Applying these principles would sharpen its conceptualization.