Summary: New genetic research links anorexia nervosa with an early-morning chronotype and also identifies an increased genetic risk for insomnia in people prone to the disorder. These results contrast with many other psychiatric conditions, which are often associated with evening chronotypes, and point toward the potential of circadian-based approaches for prevention and treatment.
Researchers used genetic analyses to explore how genes tied to anorexia nervosa interact with genes that regulate the circadian clock and sleep traits. The study found a bidirectional relationship between genetic markers for anorexia nervosa and a morning chronotype (habitual early wake and sleep times). In addition, a genetic predisposition to anorexia nervosa was associated with higher risk of insomnia. Together, these findings introduce a fresh perspective on how internal biological timing may relate to the development and maintenance of anorexia nervosa.
Key Facts:
- Anorexia nervosa is associated with a morning chronotype (early rising), unlike many other psychiatric disorders commonly linked to evening chronotypes.
- The investigators applied Mendelian Randomization to assess causal relationships among genes related to anorexia nervosa, circadian regulators, and sleep traits such as insomnia.
- These genetic findings could inform future circadian-focused prevention strategies and treatments for anorexia nervosa, a disorder with high mortality and substantial relapse rates.
Source: Mass General
New findings suggest that anorexia nervosa is associated with being an early riser, in contrast to many other mental health conditions that tend to align with evening activity and sleep patterns.
The study, published in JAMA Network Open and led by investigators at Massachusetts General Hospital (MGH) with collaborators at University College London and the University of the Republic in Uruguay, examined the genetic connections between anorexia nervosa and circadian biology. The circadian clock directs daily rhythms across many physiological systems—including sleep, hormone release, metabolism, and mood regulation—so understanding its relationship with eating disorders can reveal how timing biology and behavior intersect.
To probe potential causal effects, the team applied Mendelian Randomization, a statistical approach that uses genetic variants as proxies for traits to infer directional relationships. By analyzing genetic variants associated with higher risk of anorexia nervosa and testing their influence on sleep timing and insomnia, the researchers identified a two-way association: genetic liability for anorexia nervosa increased the likelihood of a morning chronotype, and genetic markers favoring a morning chronotype increased risk for anorexia nervosa. In parallel analyses, a genetic risk score for anorexia nervosa was linked to greater insomnia risk when tested in the Mass General Brigham Biobank.
In practical terms, the results suggest that habitual early sleep and wake timing could be both a predisposing factor and a consequence of anorexia nervosa. The association with insomnia also underscores the complex sleep disturbances experienced by people with the disorder. These observations are notable because most psychiatric conditions studied to date—such as depression, binge eating disorder, and schizophrenia—have been tied to evening preference rather than morning preference.
Current treatments for anorexia nervosa remain limited and are complicated by high relapse rates (reported up to 52%) and substantial risk: anorexia nervosa carries one of the highest mortality rates among psychiatric disorders. Given this context, new insights into biological contributors like circadian timing could open additional avenues for prevention and therapy. The authors caution that clinical implications are still preliminary, but they propose that further investigation into circadian-based interventions—such as timing-focused behavioral therapies or chronotherapy—may be warranted.
“Our findings implicate anorexia nervosa as a morning disorder in contrast to most other evening-based psychiatric diseases and support the association between anorexia nervosa and insomnia as seen in earlier studies,” says senior author Hassan S. Dashti, PhD, RD, an assistant investigator in the Department of Anesthesia, Critical Care and Pain Medicine at MGH and assistant professor of anesthesia at Harvard Medical School. Lead author Hannah Wilcox, a researcher at MGH, adds that while the clinical applications are not yet defined, the results could guide future work into circadian-informed prevention and treatment strategies.
Additional contributing authors include Valentina Paz, MSc; Richa Saxena, PhD; John W. Winkelman, MD, PhD; and Victoria Garfield, PhD. The research received support from the National Institutes of Health.
About this chronotype and eating disorder research news
Author: Marcela Quintanilla
Source: Mass General
Contact: Marcela Quintanilla – Mass General
Image: The image is credited to Neuroscience News
Original Research: The findings appear in JAMA Network Open