Circadian System and Disordered Eating

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Contributed by: Lindner Center of HOPE

Circadian system (CS) refers to a complex biological system that regulates our sleep–wake cycle. The term is derived from Latin, and means “around” (circa) the “day” ( diēm), or “around the clock”. The CS has a rhythm that repeats roughly every 24 hours and is a phenomenon observed widely in nature, from plants to mammals. The circadian rhythm (CR) adjusts to the environment by external cues like light and temperature and it affects us in a variety of ways by regulating our hormone production, brain activity, cell regeneration and a variety of behaviors, including eating behaviors.

Biology of CR 

The primary circadian regulator in mammals is located in the suprachiasmatic nucleus (SCN) in in the hypothalamus in the brain. The SCN receives information related to light through the eye’s retina and passes it on to the pineal gland which is also located in the brain and serves to regulate melatonin secretion. In the dark, at night, the secretion of melatonin surges to prepare our bodies for sleep and the reverse happens in the morning with daylight. During the day, with increased light outside, the secretion of serotonin surges, contributing to boosting mood and regulating metabolism. In a way, serotonin and melatonin perform opposite functions ensuring smooth alternation of activity and rest within the 24hrs span.

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CR and Eating Disorders

The data focusing on CR and eating disorders (EDs) is overall scarce. The eating disorder with the most prominent circadian dysregulation is night eating syndrome, characterized by a circadian delay of food intake manifested by overeating in the evening and/or waking up in the middle of the night to eat. A recent review explored 21 studies that focused on the circadian abnormalities in EDs (1). The studies explored how common CR dysregulation are in EDs and the possible influence of CR on EDs. Despite widely varying samples and research methods, high rates of CR dysregulations were observed in patients across the ED spectrum, especially in the sleep/wake cycle, chronotype (how active a person is at what part of the day) and hormone secretion. A plethora of hormones, related to food intake showed dysregulation in their circadian concentrations, suggesting that those biological disturbances might be one of the root causes for ED development. Of interest, sleep disorders were demonstrated to be prevalent

in all-type EDs, possibly hinting that sleep/wake cycle dysregulation could represent a

common risk factor for all EDs. Evening chronotype, or being more active at night, which was frequently showed by patients with EDs, was also associated with specific mood and alertness problems, further perpetuating the dysfunctional eating behaviors.

How can this be used in ED treatment?

Understanding of the role of the circadian system in EDs can provide valuable insight on its potential as a new target for treatment. The armamentarium of therapeutic options for all EDs remains limited and associated with various restrictions related to side effects and availability of specialized care. For example, exposure to bright light and taking melatonin are the two well establish interventions to assist with realigning the CR (circadian synchronization). Both are accessible and with few side effects, thus providing opportunities to be considered as supplementing treatment once the biology of CR in ED is better understood. Indeed, bright light therapy used to treat disordered eating demonstrated significant improvements in both depressed mood and eating pathology for the duration of the treatment period in all EDs across numerous studies (2). Providing psychoeducation related to CR and how it affects eating behaviors might be a helpful addition when crafting a comprehensive individualized ED treatment plan. For example, to boost melatonin at night, avoiding the use of bright screens and dimming the lights can be suggested, while serotonin levels can be increased by sunlight exposure as earlier in the day as possible. Finally, the emerging field of chrononutrition focuses on the relationship between temporal eating patterns, CR, and metabolic health and might have some application to help further the research of ED/CR interplay.


  1. Circadian rhythms disruptions and eating disorders: clinical impact and possible psychopathological correlates. Giulia Menculini , Francesca BrufaniValentina Del BelloPatrizia MorettiAlfonso Tortorella . Psychiatria Danubina, 2019; Vol. 31, Suppl. 3, pp 497-502

A Systematic Review of Bright Light Therapy for Eating Disorders. Marshall T Beauchamp, Jennifer D Lundgren Prim Care Companion CNS Disord , 2016 Oct 27;18(5).

Lindner Center LogoLindner Center of HOPE offers a disciplined approach to eating disorder treatment that combines psychiatric management, psychotherapy, nutritional services, and family engagement throughout the entire process. Board-certified clinicians offer the wisdom, compassion, and proven treatment modalities to successfully treat complex illnesses such as eating disorders, returning patients, and their loved ones, to more fulfilling lives.

The Harold C. Schott Foundation Eating Disorders Program at Lindner Center of HOPE includes services for adults and adolescents, females and males, while also incorporating research.

The opinions and views of our guest contributors are shared to provide a broad perspective on eating disorders. These are not necessarily the views of Eating Disorder Hope, but an effort to offer a discussion of various issues by different concerned individuals.

We at Eating Disorder Hope understand that eating disorders result from a combination of environmental and genetic factors. If you or a loved one are suffering from an eating disorder, please know that there is hope for you, and seek immediate professional help.

Published July 22, 2021, on
Reviewed & Approved on July 22, 2021, by Jacquelyn Ekern MS, LPC