A middle-aged man of average weight presented to the sleep medicine clinic for multiple episodes of nocturnal eating during night-time awakenings for the past several months. His symptoms were more characteristic of night eating syndrome rather than sleep-related eating disorder because of his recollection of the eating episodes and intake of edible substances during these episodes. He was treated with a low dose of sertraline with an initial improvement of symptoms followed by a relapse that was controlled with an increased dose. A year after initiation of therapy, his symptoms have resolved.
- Eating disorders
- Drugs: psychiatry
- Sleep disorders (respiratory medicine)
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Nocturnal eating is a common occurrence in the general population and is underdiagnosed. The prevalence of night eating syndrome (NES) has been determined to be equal to or even greater than the classic eating disorders including anorexia nervosa and bulimia nervosa, with a prevalence rate of 1.5%–5.7% in the general population.1 2 In adults with morbid obesity or binge eating disorder, its prevalence can reach 15%.2 In 2008, investigators at the first International Night Eating Symposium in Minnesota categorised night-time eating into two diagnoses, either NES or sleep-related eating disorder (SRED). Familiarity with these relatively new syndromes can prompt clinicians to uncover and treat harmful night-time eating habits that may adversely affect quality of life and cause significant distress to the patient or those living with them.
A man in his 60s presented to the outpatient sleep medicine clinic due to ongoing episodes of night-time eating in the context of interrupted sleep occurring on average seven to eight times per night for the last 11 months. He was accompanied by his spouse who stated that his symptoms made sleeping in the same room impossible. He noted that on waking, he would consciously walk to the kitchen to consume a small amount of food before going back to sleep. When asked whether he did so as a result of hunger, he stated that his primary motive was an urge to return to sleep as quickly as possible and that he thought eating would help. He endorsed full awareness of these episodes. He denied anorexia during the day and eats several meals per day beginning with breakfast.
He has no history of depression, anxiety or restless legs syndrome. He has no other medical history and does not take any medications. He is a non-smoker, does not drink alcohol and does not take any sedative–hypnotic drugs. His work schedule involved travel across time zones and he was on a rotating shift work schedule. He has not noticed his symptoms worsening after travel or shift work. He endorsed snoring, sleep apnoea and daytime fatigue with an Epworth Sleepiness Scale score of 8/24. He has no relevant family history.
Physical exam showed blood pressure of 118/76 mm Hg, pulse rate of 48 beats/min, weight of 202 pounds, and a height of 6 ft 0.5 inch. His body mass index was 27. The rest of the physical exam was normal. He reported being an athlete, and his resting heart rate regularly trends below 60 beats/min.
Video monitored polysomnography was done to rule out a primary sleep disorder. It showed evidence of sleep maintenance insomnia and mild obstructive sleep apnoea with an apnoea hypopnoea index of 6.2/hour and a minimum O2 saturation of 87%. Nocturnal eating episodes were not observed in the sleep laboratory. A night-time eating disorder should not be ruled out based on this finding, given the patient history.
When faced with nocturnal eating, two diagnoses must be on the differential: NES and SRED. The main differences between NES and SRED are personal awareness of night-time eating, subsequent recollection of the episode, and types and amounts of foods ingested. Table 1 summarises these main differences and compares them to our patient. A diagnosis of NES is given to an individual who retains awareness of night-time eating, recalls the episode the following day and ingests a controlled amount of food similar to that eaten during the day. In contrast, a diagnosis of SRED involves an individual with decreased or absent awareness and recollection of nocturnal eating who often ingests an uncontrolled amount of food akin to bingeing and is likely to consume toxic substances or unpalatable foods, such as raw meat or soap.1 3 While both are associated with obesity and mood disorders, SRED is also associated with primary sleep disorders such as sleepwalking, restless leg syndrome and obstructive sleep apnoea.
The diagnosis of NES is based on a set of criteria proposed by Allison et al in 2010.4 Our patient meets all six criteria. For the first criterion, the patient must show a significant increased intake of food during the evening and/or night-time, either through having at least two episodes of nocturnal eating per week or consuming at least 25% of daily food intake after the evening meal. For the second criterion, the patient must be aware and recall these episodes of evening and nocturnal eating. To fulfil the third criterion, a patient must have at least three of the following: (1) lack of desire to eat in the morning, (2) an urge to eat past the last meal of the day, (3) sleep onset or sleep maintenance insomnia, (4) a belief that eating would help overcome the insomnia and (5) a worsening or depressive mood in the evening. Our patient fulfils the third criterion by meeting features 3 with a polysomnography investigation and 2 and 4 through a subjective history. For the last three criteria, the patient must be distressed by these symptoms for a period greater than 3 months, and they cannot be related to any other psychiatric or medical cause. Our patient has been having these symptoms for 11 months, and they have caused great marital tension. They are not associated with substance abuse, an underlying medical or psychiatric condition, or a medication. It is estimated that 64% of individuals diagnosed with NES exhibit the triad of nocturnal hyperphagia, insomnia and morning anorexia with the clear absence of other eating disorders.5
On the other hand, the more established SRED is considered a parasomnia because ‘the eating is often involuntary and poorly recalled, thus resembling sleepwalking’.4 Parasomnias are a group of sleeping disorders characterised by abnormal behaviours while falling asleep, during sleep or while waking up. The first criterion of SRED is simply that a patient must have ‘recurrent episodes of involuntary eating or drinking occurring during the main sleep period’.5 A second criterion indicates that the patient must also experience one of the following: ‘Consumption of peculiar forms or combinations of food or inedible or toxic substances, insomnia related to sleep disruption from repeated episodes of eating with a complaint of nonrestorative sleep, daytime fatigue, or somnolence, sleep-related injury, dangerous behaviors performed while in pursuit of food or while cooking food, morning anorexia, or adverse health consequences from recurrent binge eating of high calorie food’.5 Oftentimes, patients will present with uncomfortable abdominal distension when waking up.3 Of these SRED criteria, our patient only satisfies the aforementioned first criterion but fails to meet the rest of the criteria. If one must assign this individual to either diagnostic category, his symptoms best match with those of the NES.
A 50 mg dose of sertraline per night was prescribed. His NES symptoms initially resolved within a week. However, at a 3-month follow-up, he reported recurrence of three to four episodes of nocturnal eating per night. The sertraline dose was increased to 100 mg as a result. In addition to pharmacotherapy, he was advised to limit his sleep to 7–8 hours per night and to start continuous positive airway pressure (CPAP) therapy with a therapeutic apnoea–hypopnoea index due to the obstructive sleep apnoea diagnosed during the polysomnography.
Outcome and follow-up
At the 12-month follow-up visit, he noted complete resolution of his symptoms, including the insomnia, and improvement in daytime alertness. His Epworth Sleepiness Scale score decreased from 8 points to 2 points.
Few case reports have been written about NES. One reported on a family with seven identified cases, all seven of which either suffered from a mood disorder, obesity or both.6 The underlying genetics of NES have not been studied. Our patient is unique in that he has no other medical or psychiatric condition and showed great response to pharmacotherapy.
As awareness of NES grows, investigators have focused on its treatment options. There are no unified clinical guidelines for treating NES or SRED. This case report supports the efficacy of SSRI therapy, specifically sertraline therapy, in the treatment of NES. Efficacy of sertraline therapy in NES was shown in an 8-week-long double-blind, randomised, placebo-controlled trial in which 71% of the 17 treatment group participants saw symptom resolution at a mean daily dose of 126.5 mg (±50 mg).7 Some subjects in this study did not have immediate resolution of symptoms, while others had a full remission of symptoms after 2 weeks of sertraline at the lowest dose of 50 mg/day despite having suffered from NES for decades. On average, treatment-group participants lost an average of 6.4 pounds over the 8 weeks. Our patient ultimately benefitted from an escalated sertraline dose of 100 mg along with CPAP and sleep compression therapy.
In another study, resolution of NES symptoms was documented in six of seven patients treated with an appetite suppressant with serotonergic activity D-fenfluramine, which is no longer widely available due to its effect on heart valve serotonin receptors and subsequent heart valve disease.8 This suggests night eating may be related to a dysfunction in the serotonin system as both aforementioned agents have activity on serotonergic neurons of the suprachiasmatic nucleus, which regulates the circadian rhythm. While the pathophysiology of nocturnal eating syndrome has not been clearly elucidated, imaging studies have shown increased serotonin transporter uptake in the midbrain of night eaters compared with healthy controls.9 Delayed circadian rhythm of food intake signals may also play a role.10 11
It is thought that individuals with NES have increased serotonin reuptake activity in the midbrain compared with healthy controls, leading to a relative serotonin deficiency and subsequent effects on the sleep–wake cycle, feeding behaviour and mood.2 Further trials are necessary to solidify the positive impact of SSRI therapy in the setting of nocturnal eating disorders. Interestingly, the efficacy of sertraline has been documented in SRED as well, but at an even lower dose of 25 mg per night.12
Night eating syndrome (NES) is often unrecognised by health professionals and patients despite its relatively high prevalence of up to 5% of the population.
Night-time eating in patients with obesity or mood disorders warrants investigation as a dysfunctional serotonin system may be the cause of their symptoms and can be treated with low doses of sertraline.
A typical patient with NES will recall eating edible foods to initiate or return to sleep at least two times a week.
A typical patient with sleep-related eating disorder will involuntarily ingest dangerous substances during non-rapid eye movement sleep.
Patient consent for publication
Contributors AA and NW helped with drafting and reviewing the manuscript. AJM was involved in reviewing the manuscript and managing the patient.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.