Narcolepsy is characterized by persistent daytime sleepiness, with repeated episodes of sleep throughout the day, even at inappropriate times, such as while eating.
Attacks may last from a few minutes to more than an hour. Other symptoms may include the inability to move while falling asleep or waking up (called sleep paralysis), hallucinations before falling asleep, and the temporary loss of muscle strength (cataplexy), causing the person to fall down.
In many cases, narcolepsy is due to the lack of a brain chemical that regulates sleep, possibly as a result of an immune system problem.
Treatment of narcolepsy involves regular naps and medication.