Narcolepsy is a neurological disorder that affects your ability to wake and sleep. People with narcolepsy have excessive, uncontrollable daytime sleepiness. They may also suddenly fall asleep at any time, during any type of activity.

In a typical sleep cycle, we enter the early stages of sleep, then the deeper stages, and finally (after about 90 minutes) rapid eye movement (REM) sleep. People with narcolepsy go into REM sleep almost immediately in the sleep cycle and sometimes while they’re awake.

Type 1 narcolepsy comes with a sudden loss of muscle tone that causes weakness and makes you unable to control your muscles (cataplexy). Type 2 is narcolepsy without cataplexy.

In many cases, narcolepsy isn’t diagnosed and therefore isn’t treated.

More Info: www.webmd.com