Night eating syndrome describes a condition in which a person eats a large proportion of their daily food intake at night, either after dinner or during nighttime awakenings. The condition involves symptoms found in some mood, sleep, and eating disorders, but is its own unique illness.
Researchers estimate that approximately 1.5% of people have night eating syndrome. This disorder has a prevalence of 6% to 16% in people with obesity, although it is difficult to say whether one condition causes the other. Night eating syndrome is also more common in people with depression or other psychiatric disorders.
Although night eating syndrome was first described in 1955, it received comparatively little attention from researchers until recently. We discuss what experts know so far.
Possible symptoms of night eating syndrome include:
- Habitually eating at least 25% of daily calories after dinner
- Waking up during the night to eat, at least twice a week
- Being consciously aware of night eating episodes, and able to recall them afterwards
- Skipping breakfast or feeling reluctance to eat in the morning, at least four times per week
- Cravings for food after dinner or during the night
- Trouble falling or staying asleep at least four nights per week
- The belief that eating is necessary to fall asleep
- Depressed mood, particularly at night
- Experiencing distress or negative effects on daily functioning due to night eating episodes
What Causes Night Eating Syndrome?
Experts believe night eating syndrome might arise when a person’s circadian rhythm, or internal body clock, fails to synchronize sleep and meal patterns with one another.
Usually, changing levels of appetite-related hormones allow people to sleep through the night without eating. However, people with night eating syndrome appear to have lower levels of leptin at night. Leptin is a hormone that causes feelings of fullness, so lower leptin levels might increase appetite. There may also be changes to other hormones, such as ghrelin, melatonin, cortisol, and thyroid-stimulating hormone, which regulate sleep-wake cycles, hunger, and stress levels.
A recent study found that evening people, or those who naturally prefer to sleep and wake up later, were more likely to have night eating syndrome, although research is mixed. Other studies have found that people with night eating syndrome have a delayed release of melatonin, a sleep-promoting hormone. It is unclear whether the condition may represent a delay of the body clock in general, or if eating at night may act as a cue to push the body clock later.
Night eating syndrome does not appear to discriminate based on gender, age, or socioeconomic status. However, it more commonly occurs in people with:
- Other eating disorders, such as binge eating disorder or bulimia
- Low self-esteem
- Psychiatric disorders or antipsychotic drug use
- Type 2 diabetes
- Sleep apnea
- Restless legs syndrome
Studies have found that depression and seasonal affective disorder (SAD) have a particularly strong association with night eating syndrome. Night eating symptoms may also be more intense during times of stress.
Is Night Eating Syndrome Genetic?
Some researchers believe night eating syndrome may have genetic roots. For people who are genetically predisposed, stress may trigger low serotonin levels, causing a domino effect that alters the internal body clock and interferes with feelings of fullness.
Some case studies and surveys have found that night eating syndrome could run in families, and researchers are starting to identify specific genes that could be involved.
Diagnosing Night Eating Syndrome
The current, official diagnostic criteria for night eating syndrome were established in 2008, following an international expert panel meeting. As a result, night eating syndrome was included as a standalone disorder for the first time in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) in 2013.
The Night Eating Questionnaire (NEQ) is one of the most widely used tools to diagnose night eating syndrome. The NEQ contains a series of questions designed to assess if a person’s feelings and behaviors are consistent with night eating syndrome.
Questions revolve around six general topics: morning hunger, breakfast timing, percentage of calories eaten after dinner, trouble falling asleep, nighttime awakenings, and nocturnal eating episodes. There are 14 questions in total, and participants receive a total score out of 52 to be assessed by a healthcare professional.
Another method that can be used to diagnose night eating syndrome is the Night Eating Symptom History and Inventory (NESHI), consisting of a structured interview with a healthcare professional. Physicians may use another questionnaire, the Night Eating Symptom Scale, to measure progress for someone who already has a diagnosis of night eating syndrome. A diagnosis of night eating syndrome does not require that a person’s body weight be lower or higher than average.
Some experts disagree about night eating syndrome being categorized as a unique disorder. They argue that night eating syndrome should be classified as a sub-order of bulimia, binge eating disorder, or sleep-related eating disorder. However, unlike bulimia or binge eating disorder, people with night eating syndrome do not necessarily engage in behaviors to compensate for overeating. Another difference with these conditions is that night eating syndrome episodes solely occur in the evening or at night.
So far, evidence supports the idea that night eating syndrome should be considered separate from binge eating disorder or sleep-related eating disorder, although arguments can be made that they are similar disorders.
Night Eating Syndrome vs. Binge Eating Disorder
Studies suggest that people with binge eating disorder are more likely than those with night eating syndrome to be worried about eating, weight, or body shape, as well as to binge eat with a loss of control. By contrast, people with night eating syndrome tend to eat typical or small portion sizes at night. While both disorders are connected with depression, depression and emotional eating seem to play a stronger role in binge eating disorder.
Night Eating Syndrome vs. Sleep-Related Eating Disorder
On the surface, night eating syndrome might look similar to sleep-related eating disorder21, which also involves eating large quantities of food at night. However, someone with sleep-related eating disorder is not fully awake and does not remember these eating episodes, whereas someone with night eating syndrome is fully aware while they are eating and able to recall the episode afterward.
How Does Night Eating Syndrome Impact Overall Health?
Night eating syndrome may affect body weight and sleep quality.
Night Eating Syndrome and Obesity
Obesity and night eating syndrome are linked, although not all people with night eating syndrome have excess weight. It is unclear whether night eating syndrome contributes to obesity.
Some researchers suggest that many years of eating at night might explain why older adults with night eating syndrome are more likely to be overweight or obese. Other studies have found that eating between 11 p.m. and 5 a.m. may be linked to higher weight gain. Researchers have found that eating for emotional reasons may also make it more likely for a person with night eating syndrome to have excess weight. People who feel guilt or shame about overeating may restrict calorie intake during the day and prefer to eat at night, when they have more privacy.
Night Eating Syndrome and Sleep
Although research is limited, studies suggest people with night eating syndrome may experience poor sleep quality due to waking up during the night to eat. They may also obtain less sleep overall, or they may sleep in later or go to bed earlier to compensate for the time spent awake at night.
Experts are still investigating the best treatment for night eating syndrome, but evidence suggests that cognitive behavioral therapy in combination with medication may be effective. Most research on medication has focused on selective serotonin reuptake inhibitors (SSRIs).
If a person with night eating syndrome also has a disorder such as depression, doctors may address this before starting therapy for night eating syndrome.
Cognitive Behavioral Therapy
Cognitive behavioral therapy (CBT) for night eating syndrome focuses on unlearning the belief that a person must eat to fall asleep. Working with their therapist, a person might record their thoughts and expectations and then test these thoughts by seeing what happens if they do not eat before sleep.
Therapy may also include adapting to eating a higher proportion of food earlier in the day, as well as keeping a sleep and food diary in order to structure overall food intake and improve sleep habits. It might help to get rid of snackable foods in the kitchen and bedroom, put motivational signs on the fridge, or establish rewards for goals achieved. In addition to addressing night eating, a healthcare professional may also provide guidance on incorporating physical activity and productive sleep hygiene habits, such as setting a regular bedtime.
Early trials have found that CBT works better for nighttime awakenings and may be less effective for reducing after-dinner snacks. Cognitive behavioral therapy for night eating syndrome may need to look different depending on whether the person struggles with weight maintenance.
Bright Light Therapy
Researchers have studied morning bright light therapy and found that it helps to improve mood, insomnia, and night eating symptoms, potentially by increasing serotonin levels.
Progressive Muscle Relaxation
Progressive muscle relaxation works by gradually moving through the body and tensing one muscle group at a time, then releasing it before moving to the next area of the body. This technique is often used to combat stress and anxiety. Preliminary evidence suggests that progressive muscle relaxation for people with night eating syndrome may help shift appetite to the morning hours and reduce negative feelings such as depression and anxiety.
Another relaxation technique that might help with night eating is deep breathing.
When to Talk to Your Doctor
Occasionally eating at night may not be a cause for concern on its own, but you should schedule a visit with your doctor if concerns about food intake or meal patterns are interfering with your health or quality of life.
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