Sleepwalking-like behavior is a frequently undiagnosed cause of patients’ obesity.

Ms. G, age 39, has a body mass index (BMI) >35 kg/m2 and is pursuing bariatric surgery to treat obesity. She is frustrated with dieting and describes a decade of unconscious nocturnal eating, including peanut butter and uncooked spaghetti.

This behavior began after her divorce 10 years ago. Initially she had partial recall of the nocturnal binges, but now describes full amnesia. Treatment for a depressive episode did not control her nocturnal eating.

Sleep-related eating disorder (SRED) can be associated with disrupted sleep, weight gain, and major chronic morbidity. In Sleep-related eating disorder (SRED)—involuntary eating while asleep, with partial or complete amnesia—the normal suppression of eating during the sleep period is disinhibited. The disorder can be idiopathic, associated with medication use, or linked to other sleep disorders such as somnambulism (sleepwalking), restless legs syndrome (RLS), periodic limb movement disorder (PLMD), or obstructive sleep apnea (OSA).

Sleep-related eating disorder (SRED) is more common in women than men; it usually begins in the third decade of life but can begin in childhood or middle age. About one-half of Sleep-related eating disorder (SRED) patients also have a psychiatric illness, usually a mood disorder. Unremitting Sleep-related eating disorder (SRED) may lead to psychopathology, as the onset of sleep-related eating usually precedes the onset of a psychiatric disorder by years.

Sleep-related eating disorder (SRED) often is unrecognized, but it can be effectively identified and treated. This article examines how to:

 
• distinguish Sleep-related eating disorder (SRED) from nocturnal eating syndrome (NES) and other disorders  
• identify precipitating causes  
• select effective pharmacologic therapy.

Differentiating Sleep-related eating disorder (SRED) from NES

Eating and sleeping—and disorders of each—are closely linked (Box). Sleep-related eating disorder (SRED) and night eating syndrome (NES) are 2 principal night eating disorders. Sleep-related eating disorder (SRED) is characterized by inappropriately consuming food after falling asleep, whereas NES is characterized by hyperphagia after the evening meal, either before bedtime or after fully awakening during the night.

To meet diagnostic criteria for Sleep-related eating disorder (SRED), patients must experience involuntary nocturnal eating and demonstrate at least 1 other symptom, such as:

 
• eating peculiar, inedible, or toxic substances  
• engaging in dangerous behavior while preparing food (Table 1).

Level of consciousness. In both Sleep-related eating disorder (SRED) and NES, patients demonstrate morning anorexia. However, patients with NES report being awake and alert during their nocturnal eating, whereas patients with Sleep-related eating disorder (SRED) describe partial or complete amnesia. Sleep-related eating disorder (SRED) patients with partial awareness often describe the experience as being involuntary, dream-like, and “out-of-control.” Interestingly, hunger is notably absent during most episodes in which patients have at least partial awareness.

Typically, patients cannot be awakened easily from a sleep-eating episode. In this regard, Sleep-related eating disorder (SRED) resembles sleepwalking. Sleepwalking without eating often precedes Sleep-related eating disorder (SRED), but once eating develops it often becomes the predominant or exclusive sleepwalking behavior. This pattern has led many researchers to consider Sleep-related eating disorder (SRED) a “sleepwalking variant disorder.”

Eating episodes in Sleep-related eating disorder (SRED) are often characterized by binge eating, and many patients describe at least one episode per night. They usually eat high-calorie foods. The spectrum of cuisine is broad, ranging from dry cereal to hot meals that require more than 30 minutes to prepare. Patients treated at our sleep center report eating foods that are high in simple carbohydrates, fats, and—to a lesser extent—protein. Peanut butter—a preferred item—can lead to near-choking episodes when patients fall asleep with peanut butter in their mouths and wake up gasping for air. Alcohol consumption is rare.

Sleep-related eating disorder (SRED) episodes can be hazardous, with risks of drinking or eating excessively hot liquids or solids, choking on thick foods, or receiving lacerations while using knives to prepare food. Patients may consume foods to which they are allergic or eat inedible or even toxic substances (Table 2).