Narcolepsy in a Young Adult Initially Misdiagnosed as Depression: A Case Report

Abstract

Narcolepsy is a chronic neurological sleep disorder characterized by excessive daytime sleepiness (EDS) and rapid eye movement (REM) sleep related phenomena such as cataplexy, hallucinations, and sleep fragmentation. Owing to significant overlap with psychiatric symptoms, particularly depression, narcolepsy is frequently misdiagnosed, resulting in delayed treatment and impaired functional outcomes. We report the case of a young adult male who presented with an 18-month history of severe daytime sleepiness, declining academic performance, and reduced motivation. He was initially diagnosed with major depressive disorder and treated with fluoxetine for six months without clinical improvement. Detailed sleep history later revealed episodes of cataplexy and hypnagogic hallucinations. Overnight polysomnography excluded obstructive sleep apnoea, and Multiple Sleep Latency Test (MSLT) demonstrated a mean sleep latency of four minutes with three sleep-onset REM periods, fulfilling ICSD-3 diagnostic criteria for narcolepsy type 1. The patient was started on modafinil therapy, resulting in marked improvement in alertness and academic performance within two weeks. This case highlights the importance of maintaining a high index of suspicion for narcolepsy in young patients with persistent fatigue unresponsive to antidepressants. Early recognition and appropriate sleep evaluation are essential to prevent prolonged misdiagnosis and ensure timely management.