Night Eating Syndrome

Night eating syndrome is an eating disorder associated with sleep fragmentation, causing people to wake up at night to eat and potentially leading to poor sleep quality and various chronic health problems, including cardiovascular disease and diabetes. We will explore the causes and impacts of night eating syndrome, as well as feasible methods to control its symptoms.

What Is Night Eating Syndrome?

Night eating syndrome refers to a condition where a person consumes most of their daily food at night, either after dinner or when waking up at night. Researchers estimate that about 1.5% of people have night eating syndrome. The symptoms of this disorder are similar to mood disorders, sleep disorders, and other eating disorders, yet it is a unique condition itself, with a prevalence of 6% to 16%. Night eating syndrome is more common in obese individuals, but it is difficult to determine if one condition is related to the other. It is also more common in people with depression or other mental illnesses.

Symptoms of Night Eating Syndrome

Possible symptoms of night eating syndrome include:

• Habitually consuming at least 25% of daily calories after dinner
• Waking up to eat at night at least twice a week
• Being consciously aware of night eating and able to recall it afterward
• Skipping breakfast or being unwilling to eat in the morning at least four times a week
• Craving food after dinner or at night
• Having difficulty falling asleep or staying asleep at least four nights a week
• Believing that eating is necessary to fall asleep
• Feeling low mood, especially at night
• Feeling distressed by night eating or having it negatively impact daily life

Risks of Night Eating Syndrome

Night eating syndrome may affect weight and sleep quality. Although research is limited, studies show that people with night eating syndrome may have poorer sleep quality. Due to waking up to eat at night, they may also get less overall sleep or sleep later or earlier to make up for awake night time.

There is an association between obesity and night eating syndrome, but not all night eating syndrome patients are overweight. Researchers have found that emotional eating may make night eating syndrome patients more prone to overweight. However, it is unclear whether night eating syndrome causes obesity.

What Causes Night Eating Syndrome?

Experts believe night eating syndrome may be triggered by a mismatch between the body’s circadian rhythm of sleep and eating patterns. Normally, fluctuations in appetite-related hormones keep people asleep without eating, but in night eating syndrome patients, hormones regulating sleep, hunger, and stress, such as melatonin and leptin, change. Recent studies have found that people who go to bed late (natural night owls) are more prone to night eating syndrome. Other research has found delayed release of melatonin (a sleep-promoting hormone) in night eating syndrome patients. It is unclear whether this is evidence of a general delay in the circadian clock or a cause of the circadian delay due to night eating.

Night eating syndrome does not seem more common in specific genders, ages, or socioeconomic groups. It is more common in people with:

• Other eating disorders, such as binge eating disorder or bulimia nervosa
• Depression
• Insomnia
• Anxiety
• Low self-esteem
• Mental illness or use of antipsychotic medications
• Smoking habits
• Type 2 diabetes
• Sleep apnea
• Restless legs syndrome

Studies have found a particularly close association between depression and seasonal affective disorder (SAD) with night eating syndrome. Night eating symptoms may also be more severe during stressful times.

Is Night Eating Syndrome Hereditary?

Some researchers believe night eating syndrome may be genetic. For people with a genetic predisposition, stress may cause serotonin levels to drop, triggering a domino effect that disrupts the circadian clock and affects satiety.

Some case studies and surveys have found that night eating syndrome may run in families, and researchers are beginning to identify specific genes that may be involved.