When does narcolepsy cause cataplexy?
There are two main types of narcolepsy - narcolepsy with cataplexy and narcolepsy without cataplexy. You may ask, what is cataplexy? Cataplexy is a sudden and uncontrollable muscle weakness or paralysis that is often triggered by a strong emotion, such as excitement or laughter.
People who experience cataplexy as one of their narcolepsy symptoms often times have low levels of hypocretin, while those who do not experience cataplexy symptoms have normal levels of hypocretin. Hypocretin, also known as orexin, is a brain chemical that regulates arousal, wakefulness and apptetite.
Some reasons that people with narcolepsy may be producing low levels of hypocretin include:
- Autoimmune disorders that cause a loss of the brain cells that produce hypocretin
- Brain injuries that specifically impact the section of the brain that controls wakefulness and REM sleep
- Family history of narcolepsy with cataplexy