Night eating syndrome (NES) is an eating disorder, which is primarily characterized as an ongoing, persistent pattern of late-night binge eating. It was originally described by Dr. Albert Stunkard in 1955  and is currently included in the “Other Specified Feeding or Eating Disorder” category of the DSM-5. Research diagnostic criteria have been proposed  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 morning hunger, urges to eat in the evening/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, between 1 and 2% of the general population, and approximately 10% of obese individuals. The age of onset is typically in adulthood, with children rarely reporting NES. 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. 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.
Symptoms and behavior
The research diagnostic criteria for NES  include:
- The daily pattern of eating demonstrates a significantly increased intake in the evening and/or nighttime, as manifested by one or both of the following:
- At least 25% of food intake is consumed after the evening meal
- At least two episodes of nocturnal eating per week
- Awareness and recall of evening and nocturnal eating episodes are present.
- The clinical picture is characterized by at least three of the following features:
- Lack of desire to eat in the morning and/or breakfast is omitted on four or more mornings per week
- Presence of a strong urge to eat between dinner and sleep onset and/or during the night
- Sleep onset and/or sleep maintenance insomnia are present four or more nights per week
- Presence of a belief that one must eat in order to initiate or return to sleep
- Mood is frequently depressed and/or mood worsens in the evening
- The disorder is associated with significant distress and/or impairment in functioning.
- The disordered pattern of eating has been maintained for at least 3 months.
- The disorder is not secondary to substance abuse or dependence, medical disorder, medication, or another psychiatric disorder.
The DSM-5 diagnostic criteria for NES  are as follows:
- Repeated occurrences of night eating, demonstrated by eating after waking from sleep or by an excess in food intake after the evening meal.
- The individual is aware of and can recall the eating.
- Other influences such as changes in the individual’s sleep-wake cycle or social norms cannot better explain the night eating.
- Significant distress and/or impairment in functioning results from the night eating.
- The disordered pattern of eating is not caused by binge-eating disorder, a mental disorder, a medical disorder, or the effect of medication.
Treatment for NES includes the selective serotonin reuptake inhibitors, Cognitive-Behavioral Therapy, progressive muscle relaxation, and behavioral weight loss. Bright light therapy might also be a treatment option. No other therapies have been tested. There is no support for therapies that affect melatonin or leptin. Several years ago there was a belief that night eating was associated with carbohydrate craving, but research has failed to support this theory.
NES is sometimes associated with excess weight; as many as 28% of individuals seeking gastric bypass surgery were found to suffer from NES in one study. However, not all individuals with NES are overweight. Night eating has been associated with diabetic complications. Many people with NES also experience depressed mood  and anxiety disorders.
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