1338 SSRI-Induced REM Sleep Behavior Disorder with Symptom Resolution After Antidepressant Discontinuation

Abstract Introduction Rapid eye movement (REM) sleep behavior disorder (RBD) associated with selective serotonin reuptake inhibitors (SSRIs) is considered extremely rare, even though serotonergic antidepressants are widely prescribed. Many patients taking SSRIs may show subtle REM sleep without atonia (RSWA) on polysomnography, but very few develop true RBD with dream-enactment behaviors. We describe a case of SSRI-associated RBD confirmed on polysomnography, with complete resolution of symptoms following withdrawal of the medication. Report of case(s) A 45-year-old man with PTSD, nightmare disorder, bipolar disorder, and anxiety presented with a 15-year history of dream enactment behaviors including shouting, punching, and falling out of bed, resulting in recurrent injuries. Symptoms suspected to have begun after initiation of fluoxetine, which he had remained on for over a decade. Initial PSG in 2024 showed markedly reduced sleep efficiency without REM sleep. Repeat PSG in January 2025 demonstrated RSWA with a documented episode of dream enactment during REM sleep (sitting up and picking at the bed sheets). AHI was 1.8, excluding obstructive sleep apnea as a contributing factor. While awaiting psychiatric coordination to wean off Fluoxetine, he was treated with melatonin titrated to 6 mg nightly, which reduced the frequency and severity of behaviors but did not eliminate them. After psychiatric clearance, Fluoxetine was tapered and discontinued. Within several weeks, the patient experienced complete resolution of dream enactment behaviors and nightmares. A brief recurrence occurred after initiation of Vilazodone, which again resolved after discontinuation. He remained asymptomatic on melatonin alone, which was subsequently tapered. Conclusion SSRI-induced RBD is rare but clinically significant. This case demonstrates the importance of recognizing medication-associated parasomnias, confirming RSWA on PSG, coordinating antidepressant modification, and using interim symptom-targeted therapy to prevent injury. Resolution after SSRI withdrawal supports a causal relationship. Support (if any)