'Sleep attacks' can occur at unusual times, such as during a meal or in the middle of a conversation. Affected individuals feel tired during the day, and several times a day they may experience an overwhelming urge to sleep. Narcolepsy is characterized by excessive daytime sleepiness. The combination of hallucinations, vivid dreams, and sleep paralysis is often frightening and unpleasant for affected individuals. Many people with narcolepsy also experience sleep paralysis, which is an inability to move or speak for a short period while falling asleep or awakening. Affected individuals often have realistic and distressing dreams, and they may act out their dreams by moving excessively or talking in their sleep. They often experience vivid hallucinations while falling asleep (hypnogogic hallucinations) or while waking up (hypnopompic hallucinations). Most affected individuals have trouble sleeping for more than a few hours at night. Although this condition can appear at any age, it most often begins in adolescence. Narcolepsy is a chronic sleep disorder that disrupts the normal sleep-wake cycle.

Cataplexy and narcolepsy definition