Narcolepsy is a neurological condition most characterized by Excessive Daytime Sleepiness (EDS), episodes of sleep and disorder of REM or rapid eye movement sleep. It is a type of dyssomnia. The main characteristic of narcolepsy is overwhelming excessive daytime sleepiness (EDS), even after adequate nighttime sleep. A person with narcolepsy is likely to become drowsy or to fall asleep, often at inappropriate times and places. Daytime naps may occur with or without warning and may be irresistible. These naps can occur several times a day. They are typically refreshing, but only for up to a couple hours. Drowsiness may persist for prolonged periods of time. In addition, night-time sleep may be fragmented with frequent wakenings.