-Original-

Sleep-Related Eating Disorder among Japanese Psychiatric Outpatients Receiving Ultra-Short-Acting Benzodiazepine Receptor Agonists: A Cross-Sectional Pilot Study

Kengo Shimoda¹, Haruki Saito^1,2, Amane Tateno², Takeshi Sakayori³ and Tsuyoshi Nogami³

¹Department of Mental Health, Nippon Medical School Chiba Hokusoh Hospital, Chiba, Japan
²Department of Psychiatry, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
³Department of Psychiatry, Nippon Medical School Hospital, Tokyo, Japan

Background: Sleep-related eating disorder (SRED) is a parasomnia characterized by involuntary nocturnal eating with amnesia, which can result in serious injuries, weight gain, and metabolic complications. Reports implicate the use of ultra-short-acting benzodiazepine receptor agonists (USBZRAs)—especially zolpidem—in SRED, but the magnitude of this risk in psychiatric patients remains unclear.
Methods: We performed a cross-sectional observational survey at two Japanese hospitals of 157 psychiatric outpatients receiving one of four USBZRAs (triazolam, zopiclone, zolpidem, or eszopiclone) for ≥7 days. High-dose USBZRA therapy was defined as the maximum recommended dose per package insert. SRED was assessed using an International Classification of Sleep Disorders-based checklist. A Firth bias-reduced logistic regression model with four prespecified clinically relevant variables was employed due to the limited number of events.
Results: Fourteen patients met SRED criteria (8.9%; 95% CI, 4.9-14.4). Zolpidem use (adjusted odds ratio [aOR] 5.98; 95% CI, 1.57-33.58) and high-dose USBZRA therapy (aOR 4.87; 95% CI, 1.56-17.51) were independently associated with SRED. Age (aOR 0.98; 95% CI, 0.94-1.02) and female sex (aOR 0.75; 95% CI, 0.22-2.87) were not significant.
Conclusions: The observed prevalence aligns with earlier reports, confirming that nearly one in eleven psychiatric outpatients receiving USBZRAs experiences SRED. Our study extends prior work by showing that SRED risk is highest at the maximum recommended dose, and especially with zolpidem. The wide confidence intervals reflect the small number of events and should be interpreted as hypothesis generating rather than definitive. These findings support limiting USBZRA dosage, favoring lower-risk hypnotics, and actively screening for nocturnal eating. This pilot study warrants validation in larger cohorts.

J Nippon Med Sch 2026; 93: 153-160

Keywords
sleep-related eating disorder, ultra-short-acting benzodiazepine receptor agonists, Z-drugs, zolpidem, high-dose therapy, somnambulism

Correspondence to
Kengo Shimoda
kshimoda@nms.ac.jp

Received, July 10, 2025
Accepted, December 17, 2025