What Is It?
Narcolepsy is a disorder that causes sudden episodes of deep sleep. These episodes can occur often and at inappropriate times, for example while a person is talking, eating or driving. Although sleep episodes can happen at any time, they may be more frequent during periods of inactivity or monotonous, repetitive activity.
Narcolepsy usually appears between ages 15 and 30, but the condition can appear earlier or later. Once it appears, narcolepsy is present for life. Men and women are affected equally.
About 60% of people with diagnosed narcolepsy have the combination of marked daytime sleepiness and sudden episodes of muscle weakness (called cataplexy). The muscle weakness can be so severe that a person with narcolepsy will collapse to the floor, but not become unconscious. This type of narcolepsy is associated with a shortage of a brain-stimulating protein called orexin (also known as hypocretin).