By Brandon R. Peters, M.D.
A few months ago, I met with a woman in Stanford's general sleep clinic who had a common complaint: restless sleep. However, upon further questioning, it became clear that she had a slightly more unusual problem. For many years, she experienced uncontrolled eating in her sleep, much to her consternation and embarrassment. Sleep-related eating disorder is actually surprisingly common, especially in the setting of sleeping pill use, and its features are worth exploring to understand the nature of consciousness itself.
Over the past 10 years, 51-year-old Mary (not her real name) has had a problem she has largely kept to herself. It seemed to start around the time of her divorce, when she developed difficulty sleeping at night, with frequent awakenings. Even more disturbing to her, Mary began to have episodes of eating in the night.
She would often awake to find evidence from her prior night's activities, discovering wrappers and empty yogurt containers near her bed the next morning. Once she awoke and, noting the mess in her bed, responded, "Oh, peaches." She frequently eats mostly sweet things at night and acknowledges craving carbohydrates during the day. One night she ate an entire bottle of ketchup.
During the episodes, Mary would feel that she was somehow "subconscious." She sometimes recalled nothing at all, but more often she would have a vague recollection of the activities the next morning. In thinking back on the episodes, she says that she would often feel like she was a kid doing something bad. There was never any will or volition involved. Her typical good judgment fell by the wayside. As Mary said, "You don't care if you eat 100 cookies."
Her actions go beyond consuming food with attempts at cooking. She will often make a "fake" cookie dough, mixing most of the ingredients together, and then will eat the entire bowl of it. She frequently gets in trouble for unconsciously eating her roommate's food.
These occurrences were commonplace for Mary, happening at least five times per week. Fortunately, she never had violent actions during her sleep and she had no history of sleepwalking out of the house. She warns others about her behaviors, and she can typically be redirected back to her bedroom if she is observed to be up.
As a result of her frequent sleep eating, Mary has to exercise several hours during the day to keep her weight down. Despite this, she believes she is 15 to 20 pounds above her ideal body weight. She has a history of bulimia when she was a teen and younger adult. Her examination was normal at her clinical evaluation, including a normal weight, though she had signs suggestive of sleep apnea and this was confirmed with an overnight sleep study. She was also provided information about sleep-related eating disorder.
There are two conditions that are currently used to classify abnormal eating overnight: night eating syndrome and sleep-related eating disorder (SRED). The former consists of a fully awake person who engages in compulsive eating at night, typically due to abnormalities of the hypothalamic-pituitary axis. The latter is far more common, and applies to Mary's situation.
Sleep-related eating disorder consists of recurrent episodes of involuntary eating and drinking during arousals from sleep with problematic consequences. Eating may occur quickly, with episodes lasting less than 10 minutes. The events occur in an involuntary or out of control manner after an interval of sleep. As in Mary's case, the episodes usually occur during partial arousals with partial recall, but difficulty rousing and no recall may occur. Some people report substantial alertness with full recall.
SRED may involve the consumption of peculiar forms or combinations of food or of inedible or toxic substances. Reports include consuming a variety of items, nearly anything imaginable, including: frozen pizzas, raw bacon, buttered cigarettes, cat food, salt sandwiches, coffee grounds, ammonia and cleaning solutions. These behaviors may lead to insomnia from sleep disruption. They can also be dangerous, resulting in cuts, burns, poisoning or other injuries. In the morning, a lack of appetite and a bloated stomach may often be present. Weight gain, diabetes and other long-term health consequences may occur.
Most people with SRED report nightly episodes, even multiple times per night. Many prefer to indulge in eating high-calorie foods. The foods consumed may not even be particularly desirable -- one patient I am familiar with ate carrots at night, even though she despised them during the day. (Why she owned carrots, I am not sure.) Hunger and thirst are not the cause of the eating. There may be associated dreams with the behaviors that correspond to the actions.
The food preparation that occurs in SRED can be quite elaborate. Simple foods or an entire hot or cold meal may be prepared and consumed. Sloppy food handling is common. Alcohol is almost never consumed. Interference in these actions may provoke irritability and agitation.
Sleep-related eating is surprisingly common, and the widespread use of sleeping pills may be increasing the incidence. A survey of university students found that 4.6 percent of people had experienced sleep-related eating, with women making up the vast majority (up to 83 percent of those afflicted). It is more than twice as common among those with a history of an eating disorder, as Mary had. Though it often starts in a patient's 20s, embarrassment and other factors may delay diagnosis for 10 to 15 years.
What causes sleep-related eating? In many cases, the cause remains unknown. However, it is commonly associated with another primary sleep disorder such as obstructive sleep apnea or restless legs syndrome. It is more common among people with a history of sleepwalking, and once eating becomes part of the behavior, it predominates. Medications may be an important trigger, especially sleeping pills like Ambien and Halcion. Other medications that affect the brain (like Lithium and Zyprexa) may also play a role. Sleep eating may also occur in the setting of smoking, alcohol, or other illicit substance cessation.
There are other rare causes of the condition. It may begin after an acute stress or in the context of daytime dieting. It has been reported with the onset of narcolepsy or with other medical conditions such as autoimmune hepatitis and encephalitis. As stated above, it frequently coexists with daytime eating disorders like anorexia and bulimia.
Why does sleep-related eating occur with an altered state of consciousness? How can someone cook and eat with only a partial awareness and recollection? This is one of the most interesting aspects of this condition. This likely represents the final outcome of multiple potential pathways that lead to an admixture state of consciousness, in which features of wakefulness and sleep occur simultaneously within the brain. The unifying explanation for this is unknown. When sleep studies are conducted, another sleep disorder is identified in 80 percent of cases. The study may reveal multiple confusional arousals, with or without eating, and wakefulness demonstrated on the EEG of the brain waves.
Fortunately, there are effective treatment options for those who suffer from sleep-related eating. The most important first step is to consult with a sleep specialist and identify and treat any concomitant sleep disorders like sleep apnea and restless legs syndrome. Safety precautions must be observed to minimize the risk of harm. Known precipitants, especially sleeping pills, must be avoided. Sleep deprivation should be minimized as this may worsen the condition. In addition, medications may also be used, including Topamax.
If you experience frequent episodes of sleep-related eating, don't suffer in silence. Speak with your doctor about these occurrences so that the cause can be identified. When necessary, the proper treatment can be initiated to finally put your uncontrollable midnight snacking to bed.
Brandon R. Peters, M.D., is the writer on sleep for About.com, a neurology-trained sleep medicine specialist in Novato, Calif., and adjunct clinical faculty at the Stanford Center for Sleep Sciences and Medicine. This Center is the birthplace of sleep medicine and includes research, clinical, and educational programs that have advanced the field and improved patient care for decades. To learn more, visit us at: http://sleep.stanford.edu/.
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"The International Classification of Sleep Disorders: Diagnostic & Coding Manual." American Academy of Sleep Medicine, 2nd Edition. 2005.
Kryger, MH et al. "Principles and Practice of Sleep Medicine." Elsevier, 5th edition. 2011.