Narcolepsy is a sleep disorder caused by the lack of an important chemical in the brain that controls sleep and wake cycles. It is characterized by daytime sleepiness, cataplexy, sleep paralysis, and instant REM sleep. Around 1 in 2000 Americans have narcolepsy. Studies have shown narcolepsy is linked to a loss of hypocretin neurons in the hypothalamus which regulate wakefulness. There is no cure, but medications can help manage symptoms like sleepiness, cataplexy and hallucinations.