Night eating syndrome

Night eating syndrome (NES) is an eating disorder, characterized by a delayed circadian pattern of food intake.^[1] Although there is some degree of comorbidity with binge eating disorder,^[1] it differs from binge eating in that the amount of food consumed in the night is not necessarily objectively large nor is a loss of control over food intake required. It was originally described by Albert Stunkard in 1955^[2] and is currently included in the other specified feeding or eating disorder category of the DSM-5.^[3] Research diagnostic criteria have been proposed^[1] and include evening hyperphagia (consumption of 25% or more of the total daily calories after the evening meal) and/or nocturnal awakening and ingestion of food two or more times per week. The person must have awareness of the night eating to differentiate it from the parasomnia sleep-related eating disorder (SRED). Three of five associated symptoms must also be present: lack of appetite in the morning, urges to eat at night, belief that one must eat in order to fall back to sleep at night, depressed mood, and/or difficulty sleeping.

NES affects both men and women,^[4] between 1 and 2% of the general population,^[5] and approximately 10% of obese individuals.^[6] The age of onset is typically in early adulthood (spanning from late teenage years to late twenties) and is often long-lasting,^[7] with children rarely reporting NES.^[8] People with NES have been shown to have higher scores for depression and low self-esteem, and it has been demonstrated that nocturnal levels of the hormones melatonin and leptin are decreased.^[9] The relationship between NES and the parasomnia SRED is in need of further clarification. There is debate as to whether these should be viewed as separate diseases, or part of a continuum.^[10] Consuming foods containing serotonin has been suggested to aid in the treatment of NES,^[11] but other research indicates that diet by itself cannot appreciably raise serotonin levels in the brain.^[12] A few foods (for example, bananas^[12]) contain serotonin, but they do not affect brain serotonin levels,^[12] and various foods contain tryptophan, but the extent to which they affect brain serotonin levels must be further explored scientifically before conclusions can be drawn,^[12] and "the idea, common in popular culture, that a high-protein food such as turkey will raise brain tryptophan and serotonin is, unfortunately, false."^[12]