Narcolepsy

Narcolepsy is a chronic sleep disorder characterized by an inability in the brain to regulate the body's sleep-wake cycle. Excessive daytime sleepiness (EDS) is the main symptom and may also cause muscle weakness. People who have narcolepsy often fall into deep REM sleep quickly and wake up directly from it. This is linked to vivid dreams while waking up and falling asleep. A chemical in the brain, called Hypocretin, helps control levels of wakefulness. Most people with narcolepsy have low levels of this chemical. What causes these low levels isn't exactly understood.