New research suggests that the eating disorder anorexia nervosa is more likely to be associated with early risers, unlike many other disorders that tend to occur in the evening, such as depression, binge eating disorder and schizophrenia. The study, published in JAMA Network Open and led by researchers at Massachusetts General Hospital (MGH) in collaboration with University College London and the University of the Republic in Uruguay, also shows a link between anorexia nervosa and the risk of insomnia .

Eating Disorders and The Internal Clock

Eating disorders are serious illnesses that are associated with significant morbidity, mortality and suffering. People suffering from eating disorders often feel shame, isolation and face stigma. Anorexia nervosa is a common condition that affects more women than men. Those affected eat extremely little food, which can lead to severe physical deficiency symptoms and health problems over time. In fact, anorexia is associated with the highest mortality and suicide rates. Compared to healthy peers, women with anorexia are up to 12 times more likely to die from any cause over the same period, and about 57 times more likely to die by suicide.

Previous research suggests a possible connection between eating disorders and the body’s internal clock, the circadian clock, which controls a variety of biological functions such as sleep and affects nearly every organ in the body. This study aimed to better understand this connection by examining genes associated with anorexia nervosa, the circadian clock, and several sleep traits, including insomnia.

Early Risers are More Likely to Suffer From Anorexia

The researchers used a statistical method called Mendelian randomization to explore how genes associated with a particular trait affect other traits of interest. For example, studying the sleep patterns of people with genetic differences that increase the likelihood of anorexia nervosa provides evidence of the connection between anorexia nervosa and sleep. They found a reciprocal relationship between genes associated with anorexia nervosa and genes related to morning chronotype (waking up early and going to bed early).

In other words, the results suggest that early risers are at increased risk of anorexia nervosa, and that the illness could lead to getting up earlier. The team also found a link between anorexia nervosa and insomnia. When they further examined the link between insomnia using the Mass General Brigham Biobank and developed a “genetic risk score” for anorexia nervosa, the scientists found that the genetic risk score was actually associated with a higher risk of insomnia.

These results, according to the researchers, suggest that anorexia nervosa is a morning disorder, unlike most other evening psychiatric disorders, and support the link between anorexia nervosa and insomnia as observed in previous studies. Treatment options for anorexia nervosa are limited, and current treatments have relapse rates as high as 52%. In addition, the cause of the disease is still unclear. Because anorexia nervosa has the second highest mortality rate among psychiatric disorders, more research into new prevention strategies and treatments is urgently needed. The current research results could herald future investigations into circadian-based therapies to treat and prevent anorexia.

A particularly promising psychological treatment currently is enhanced cognitive-behavioral therapy. It was found that a remarkable number of those who completed the treatment were able to maintain their gains five years after treatment. However, the most important predictor of a positive outcome in anorexia is early detection and intervention. In general, the longer the disease takes before treatment, the worse the prognosis.