Narcolepsy is a neurological disorder affecting the regulation of sleep and wakefulness. It is characterized by excessive daytime sleepiness, cataplexy, and other rapid eye movement (REM) sleep-associated manifestations (eg, hypnagogic hallucinations and sleep paralysis). The recognition of this disorder is usually delayed by 10 to 15 years, largely because of its protean manifestations, insidious nature, and lack of physician awareness. Delayed diagnosis is associated with poor quality of life, depression, and increased likelihood of accidents. Health care providers should include narcolepsy in the differential diagnosis of patients with excessive sleepiness, chronic fatigue, sleep-disordered breathing, depression, and attention-deficit/hyperactivity disorder. Narcolepsy is a lifelong disorder that often requires pharmacological treatments, which may include wake-promoting stimulants for excessive sleepiness and gamma-hydroxybutyrate (sodium oxybate) and antidepressants for REM sleep-associated manifestations. This article presents a case of a 47-year-old man with long-standing sleepiness and cataplexy who was eventually diagnosed with narcolepsy 30 years after the first onset of symptoms. The presenting manifestations of narcolepsy, diagnostic criteria, and its management are also discussed.