Night Eating Syndrome
The most likely diagnosis is night eating syndrome (NES), not sleep-related eating disorder, based on the patient's full awareness and memory of eating episodes, the presence of evening urges to eat before sleep, and the partial response to topiramate. 1
Distinguishing Features Supporting NES Diagnosis
The key diagnostic features present in this patient that differentiate NES from other nocturnal eating disorders include:
Full awareness and complete memory of eating episodes - This is the critical distinguishing feature. NES patients are fully conscious during nocturnal ingestions, whereas sleep-related eating disorder (SRED) is characterized by amnesia or only partial awareness of eating episodes 2, 1
Evening hyperphagia with urges to eat before sleep - The patient reports feeling an urge to eat before falling asleep, which is a core feature of NES representing a delay in the circadian timing of food intake 1, 3
Daytime fatigue and weight gain - These are expected consequences of NES, as sleep is disrupted in the service of food intake and repeated nocturnal snacking leads to positive energy balance 1
Association with anxiety disorder - NES commonly co-occurs with mood and anxiety disorders, which this patient has in her history 4
Why Other Diagnoses Are Excluded
Sleep-related eating disorder (SRED) is ruled out because the patient has full memory of episodes. SRED is distinguished by parasomnic nocturnal ingestions with amnesia, consumption of non-typical or dangerous items, and frequent association with other sleep disorders like restless leg syndrome or medication effects (particularly zolpidem) 2, 1
REM sleep behavior disorder involves dream enactment behaviors during REM sleep, not eating behaviors, making it irrelevant to this presentation 2
Sleep-related epilepsy would not present with this pattern of conscious, purposeful eating behavior with full memory and would typically have other neurological manifestations 2
Clinical Significance of Topiramate Response
The partial response to topiramate supports the NES diagnosis, as topiramate has been proposed as a treatment option for NES based on its efficacy in eating disorders 1. While the evidence for topiramate in NES specifically is limited, it has shown promise in related eating disorders with comorbid mood disturbances 5. The American Gastroenterological Association notes topiramate's mechanism may involve increasing GABA receptor activity and inhibiting glutamate receptor activity, which could address the neurochemical disturbances underlying NES 6
Treatment Approach for This Patient
The most evidence-based pharmacological treatment for NES is sertraline (an SSRI), which has demonstrated efficacy in clinical trials by addressing the hypothesized serotonergic dysfunction underlying the syndrome 1, 3. Since topiramate has provided only partial benefit, consider:
Adding or switching to sertraline as the primary pharmacological agent, as it has the strongest evidence base for NES treatment 1, 3
Optimizing topiramate dosing if continuing it - the typical range for eating disorders is 100-400 mg daily, and the patient may not yet be at an adequate dose 6
Combining pharmacotherapy with cognitive behavioral therapy (CBT), which has shown effectiveness for NES and addresses the behavioral and circadian rhythm components 3
Considering phototherapy to help resynchronize the delayed circadian pattern of food intake characteristic of NES 1
Critical Clinical Pitfall
Do not confuse NES with SRED based solely on nocturnal eating behavior. The presence or absence of awareness and memory during eating episodes is the critical distinguishing feature that determines diagnosis and treatment approach 2, 1. SRED would require evaluation for underlying sleep disorders and elimination of provocative medications, whereas NES requires treatment targeting circadian rhythm desynchronization and serotonergic dysfunction 2, 3