What Is Night Eating Syndrome?

Night eating syndrome is an eating disorder characterised by recurrent incidences of food consumption during the evening, often supplemented by disruptions in sleep patterns, along with feelings of depression and distress.

Introduction

Eating disorders have been puzzling experts for decades, as they represent mental health conditions that affect approximately 20 million people in Europe alone.¹ They can be defined as abnormal eating behaviours with an unfavourable impact on both physiological and psychological activities. The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) establishes the updated term ‘Feeding and eating disorders’, referring to eight distinct categories of eating disorders, with night eating syndrome (NES) falling under ‘Other specified feeding or eating disorders’.² More accurately, NES is officially diagnosed as an eating disorder marked by recurrent episodes of late-night eating and/or waking up during the night to eat. These characteristics, along with additional associated symptoms discussed below, serve as diagnostic hallmarks for NES.³

Despite increased awareness and recognition of eating disorders as mental health conditions with serious consequences, NES only recently gained attention in research studies, making it a complex topic with numerous risk factors and treatment options that are not yet fully explored. The estimated prevalence of NES indicates that 1 to 2% of the entire population may experience this condition, constituting 2.8 to 8.2% of all eating disorders.³ It remains arguable whether factors such as age, sex, and sociocultural features influence the incidence of NES. Nevertheless, a higher prevalence is observed among obese individuals assigned female at birth (AFAB)  compared to obese individuals assigned male at birth (AMAB), and a general adverse impact is detected in individuals AFAB  over individuals AMAB.⁴

NES is associated with various complications, including obesity and diabetes. Individuals with NES are encouraged to seek help from experts to identify potential contributing factors and delve into available treatment options.

Causes and risk factors

Scrutinising the factors contributing to NES is pivotal for incorporating effective prevention strategies and analysing innovative treatment plans. Although the exact aetiology of NES remains elusive, several predictive factors have been identified:

1. Circadian rhythms and sleep patterns disruption: the circadian rhythm involves the internal body clock that regulates processes such as sleep, alertness, appetite, and temperature over  24 hours. An impairment in this rhythm, characterised by a delay in the eating and sleeping routines due to abnormal hormone release, can lead to nocturnal hunger and wakefulness.^5,6
2. Biological factors: lowered melatonin and leptin levels, hormones that are typically secreted at night, are observed in NES patients during nighttime⁷, whilst cortisol levels, linked to stress and overeating, are elevated.⁴ Moreover, altered serotonin and dopamine levels further modulate the circadian rhythm. Individuals with NES attempt to increase serotonin levels, enhancing mood and sleep, by resorting to nighttime eating.⁵
3. Psychological factors and other eating disorders: traits of depression, anxiety, and insomnia contribute to emotional discomfort that people try to confront through nighttime eating. Other eating disorders, such as binge eating disorder, bulimia nervosa, and anorexia nervosa, have also been linked to the progression of NES.⁸
4. Genetic influences: similar to other eating disorders, NES may exhibit a hereditary pattern as the likelihood of developing NES increases in individuals with a first-degree relative affected by this condition.⁴
5. Other pathologies: while NES can occur in people with normal body weight, it is more prevalent in those with obesity, including patients undergoing bariatric surgery.⁹
6. Diet and personal image: Dietary practices and restrictions during the day contribute to eating episodes at night.³ Impulsivity and specific personal traits are associated with overeating, necessitating consideration when discussing potential therapeutic approaches.⁹

Diagnostic criteria of night eating syndrome

Seeking professional help, undergoing a medical and psychological evaluation, and cultivating collaboration with healthcare providers, for instance, by responding accurately to night eating questionnaires, serve as pivotal steps in distinguishing NES and exploring treatment options. More specifically, NES has been suggested as a possible diagnosis under the following criteria:⁵

1. Evening hyperphagia: an excessive food intake with at least 25% of the total daily food consumed after dinner and/or waking up at night to eat, occurring at a minimum of two times per week
2. Conscious overeating: being aware of eating episodes during the night and being able to recall them the next day
3. Three out of the five following criteria:
   1. Morning anorexia: Loss of appetite after waking up and/or no desire for breakfast observed four or more times per week
   2. Cravings to eat: Extreme desire to eat between dinner and sleep and/or at night
   3. Insomnia: Inability to fall asleep and/or stay asleep throughout the night, occurring at least four times per week
   4. Conviction that consuming food before sleeping is essential
   5. Depressive attitude or bad mood in the evening
4. Physical or mental distress and/or debilitation in physiologic processes
5. Symptoms that last a minimum of three months
6. Identifying this syndrome as the primary cause of impairment when compared to other mental disorders

Treatment options

A range of treatment options are available for patients with NES, mainly emphasising psychotherapeutic modifying techniques, pharmacological agents, as well as education on diet and nutrition. Notable treatment options include:^3,4

• Cognitive-behavioural therapy (CBT): CBT is a non-pharmacological psychotherapy technique that has been proven effective in supporting and encouraging patients with NES to acknowledge their actions and limit their behaviours
• Progressive muscle relaxation (PMR): PMR, alone or in combination with exercise, guides patients on how to modulate muscle tension and relaxation. These methods demonstrated significantly positive results on depression and anxiety.
• Phototherapy or bright-light therapy: these techniques, involving specific wavelengths, are used in mood disorders, substantially increasing melatonin and serotonin levels, evidencing potentiality in treating NES
• Pharmacological treatment: drugs regulating serotonin levels are considered a plausible therapy for NES due to their potential to influence the circadian rhythm. Antidepressants, specifically selective serotonin reuptake inhibitors (SSRIs), like sertraline, paroxetine, and escitalopram, have been studied for their effectiveness in reducing NES symptoms and improving overall mood and quality of life.

Prognosis and long-term management

While NES can manifest as a secondary consequence of underlying conditions, it also has the potential to instigate other health issues, such as overweight, obesity, metabolic syndrome, and co-occurring eating and sleep disorders. Furthermore, NES may also contribute to adverse psychological outcomes, compromising overall mental health. Individuals with NES may encounter challenges in weight management or diabetes coping efforts.⁵ Thus, lifestyle modifications, nutritional counselling, mental health focus, and weight management are critical instruments for managing this condition and achieving a more holistic way of life.

FAQs

What are the symptoms of night eating syndrome?

NES is described by a downtrend in the circadian rhythm for food ingestion, with individuals experiencing some of the following signs:⁵

1. Eating excessively in the evening: individuals ingest at least 25% of their daily food intake post-dinner. Those with NES are fully conscious during these eating episodes and can recall them the next day.
2. Sleep disturbances: difficulty falling asleep or remaining asleep for at least four nights per week. Extreme cravings between dinner and nighttime and/or during the night, coupled with the notion that eating is essential for someone to sleep, are reported. Nightly awakenings accompanied by food intake at least two times per week are also observed.
3. Morning anorexia is a loss of appetite after waking up and/or skipping breakfast at least four times per week.
4. Mood and psychological symptoms: signs of depression and a bad mood, particularly during the evening, are described by individuals with NES. A sense of debilitation and distress lasting for prolonged periods of over three months are also some of the observed characteristics.

What other disorders can be confused with NES?

While NES has been classified as a distinct type of eating disorder, some of its symptoms may overlap with other eating disorders. For instance, binge eating disorder (BED) was found to be associated with NES, with 18-50% of BED patients³ meeting the criteria for NES diagnosis. However, BED and NES have distinct characteristics that help differentiate them. BED patients ingest significantly larger amounts of food, experience a loss of control, and may have depressive feelings not restricted to the evening but present throughout the day.  Furthermore, they may not experience insomnia and have variable motifs and impulsivity feelings that differ from those seen in NES patients.³

NES has also been correlated with sleep disorders, particularly sleep-related eating disorder (SRED). While these disorders may co-occur, SRED is characterised by symptoms such as parasomnia, an irregular sleep behaviour where people exhibit decreased levels of awareness and engage in involuntary eating episodes with no recollection of the event the following day.³

Conclusion

In summary, DSM-V has acknowledged NES as an eating disorder, marking the beginning of more in-depth investigations into this distinct syndrome. Its multifaceted profile and the coinciding symptoms render it a complex condition, often remaining underdiagnosed. Indicators such as excessive eating after dinnertime disrupted sleep patterns accompanied by food intake during unusual hours, and persistent depressive and distressed moods over an extended period may determine the development of NES or another mood, sleep or eating disorder. 

NES has been consistently linked with various conditions, including obesity, and may hinder attempts to lose weight or manage diabetes. Consequently, addressing the issue is not only beneficial in case you are on a weight loss journey but also in preventing more serious conditions. If you suspect you are experiencing NES symptoms, consult your doctor to explore the root of the problem. This proactive step could drastically improve your mental health, sleeping and eating habits.