Table 2
Typical foods consumed while sleep-eating
| Simple | Peanut butter, dry cereal, candy, bread/toast |
| Peculiar | Uncooked spaghetti, sugar/ salt sandwiches, cat/dog food, frozen food |
| Inedible/toxic | Egg shells, coffee beans, sunfl ower shells, buttered cigarettes, glue/cleaning solutions |
Chain of consequences
Repeated nocturnal binge eating episodes can have multiple adverse health effects.5,7 Patients often wake up with painful abdominal distention. Weight gain and subsequent increased BMI may compromise the control of medical complications such as diabetes mellitus, hyperlipidemia, hypertriglyceridemia, hypertension, OSA, and cardiovascular disease. Patients with SRED also report dental problems such as tooth chipping and increased incidence of caries.
Failure to control nocturnal eating can lead to secondary depressive disorders related to excessive weight gain. Moreover, SRED patients’ nighttime behaviors may disrupt their bed partners’ sleep and cause interpersonal and marital problems.
Untreated SRED is usually unremitting. In our experience, most patients describe suffering for years before seeking treatment. Many report that their symptoms have been dismissed by other physicians or wrongly attributed to a mood disorder. Not surprisingly, patients in obesity clinics and eating disorder groups regularly report SRED.
Multiple causes
Medication-induced. The commonly prescribed hypnotic zolpidem can induce SRED.10,11 Sporadic cases of SRED have been reported with other psychotropics, such as tricyclic antidepressants, anticholinergics, lithium, triazolam, olanzapine, and risperidone.12
Life stressors. For a subgroup of patients, such as Ms. G, a life stressor such as a death or divorce precipitates the disorder. Others report SRED onset with cessation of cigarette smoking, ethanol abuse, or amphetamine/cocaine abuse.5,7 Thus, SRED can be viewed as a “final common pathway disorder” that can be triggered by a variety of sleep disorders, medical-neurologic disorders, medications, and stress. It also can be idiopathic (Table 3).12
Table 3
Sleep disorders and medications associated with SRED
| Sleep disorders | Sleepwalking, obstructive sleep apnea, restless legs syndrome, circadian rhythm disorder, narcolepsy |
| Medications | Zolpidem, lithium, triazolam, olanzapine, risperidone, anticholinergics |
| Source: References 5,7-9 | |
CASE CONTINUED: Reaching a diagnosis
Ms. G’s psychiatrist refers her to an accredited sleep center, where she is instructed to keep a diary of her eating and sleeping behaviors for 2 weeks. She returns to the center and undergoes overnight video polysomnography (PSG). During this test, Ms. G demonstrates recurrent confusional arousals arising from non-rapid eye movement sleep (NREM) and eating binges while asleep with no subsequent recall.
Sleep studies aid diagnosis
Diagnosing a patient with SRED requires taking a diligent history to:
- characterize nocturnal eating
- identify predisposing or precipitating factors
- differentiate the behavior from other sleep-related or eating disorders.
At our sleep center, we frequently ask patients and their families to track the patient’s sleep and nocturnal eating behavior 2 weeks before a clinic visit. These diaries help document sleep and eating patterns and assess the patient’s awareness and subsequent recall.
As described above, recurrent nighttime eating with full awareness and control would be best characterized as NES. How-ever, there is some debate as to the extent that SRED can manifest with substantial or full alertness and subsequent recall.13 SRED and NES might be at opposite poles of a pathology continuum, in which a sub-group of patients falls into a “gray area” of mixed SRED/NES features.13,14
Self-induced emesis or other purging behavior usually is not seen in SRED. If a patient presents with this symptom, consider an alternate diagnosis such as bulimia nervosa. A patient with SRED may be diagnosed with a coexisting eating disorder, however, as long as the diagnostic features of the eating disorder are not associated with the nocturnal episodes of SRED.
Finally, at least 2 reports exist of a nocturnal dissociative disorder, in which a recurrent nocturnal “eating personality” emerges.7
Sleep laboratory testing. Overnight video PSG—recording the biophysiologic changes that occur during sleep—often is valuable in characterizing SRED and identifying other sleep disorders. To facilitate the eating behavior, we ask patients to bring to the sleep laboratory commonly consumed food to be placed within reach of their bed.
If the patient does eat during the study, we identify the sleep state (non-REM sleep or REM sleep) that precipitates the behavior. Confusional arousals, both with and without eating, usually arise from nonREM sleep.
In patients with SRED, PSG often helps to identify other sleep abnormalities that trigger arousal. Reversible disorders such as RLS, PLMD, and OSA or more subtle sleep disordered breathing are especially important to identify so they can be properly treated. Recently, PSG found rhythmic masticatory muscle activity in stages 1 and 2 non-REM sleep in 29 of 35 patients diagnosed with SRED.15