Narcolepsy is typically characterized by excessive sleepiness during the day, with a tendency to sleep at inappropriate times. There may be attacks of an irresistible, or nearly irresistible, urge to sleep. Although narcoleptics may sleep poorly at night, the daytime sleepiness of narcolepsy is generally not related to the quality of nighttime sleep.
Narcolepsy symptoms can appear all at once or develop gradually over many years. The four most common symptoms are excessive daytime sleepiness, cataplexy (sudden loss of strength in the muscles), sleep paralysis and hypnagogic hallucinations (hallucinations that occur just before falling asleep, during naps and/or on waking up). In most cases, excessive daytime sleepiness is the most bothersome symptom.
Excessive daytime sleepiness can be treated with stimulant medication and prophylactic daytime naps. When treatment is needed for the other symptoms associated with narcolepsy, SSRI antidepressants are often used.