taken from wiki, there you go...
Narcolepsy is a neurological condition most characterized by Excessive Daytime Sleepiness (EDS). The main characteristic of narcolepsy is overwhelming excessive daytime sleepiness (EDS), even after adequate night time 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 a few hours. Drowsiness may persist for prolonged periods of time. In addition, night-time sleep may be fragmented with frequent awakenings.
People with narcolepsy may dream even when they only fall asleep for a few seconds.