Sleep, circadian rhythms and eating disorders: a systematic review

Objective: As fundamental primary processes in maintaining the body's health, sleep and eating habits influence reciprocally, and this relationship is also modulated by circadian rhythms. Consistently, the literature reports various levels of alterations in sleep parameters and circadian preferences among individuals exhibiting dysfunctional eating behaviors. The present review aims to provide an up-to-date overview of case-control studies conducted to date on this topic. Method: A systematic literature search was conducted to detect case-control studies investigating both subjective and objective sleep parameters and circadian preferences in individuals with eating disorders. Thirty-three articles published between 1980 and 2025 were included. Results: Patients with eating disorders show reduced sleep efficiency, prolonged sleep onset latency, and increased arousal levels. Specifically, individuals with anorexia nervosa experience more frequent and longer nighttime awakenings, as well as reductions in both slow-wave sleep and REM sleep. In contrast, findings related to bulimia nervosa and binge eating disorder are quite inconsistent, partly due to the limited number of studies available. Overall, individuals with eating disorders tend to exhibit a preference for evening chronotypes. Discussion: This review supports the existence of an association between eating disorders and alterations in sleep and circadian rhythms. Nonetheless, current research does not provide a consistent picture of the nature, characteristics, or causality of these dysfunctions. Several factors - such as body mass index, the severity of eating disorder symptoms, and orexin levels - appear to be involved. Further investigation into these relatively understudied areas could inform the development of more effective rehabilitation strategies.