Not to be confused with Catalepsy.

Cataplexy is a sudden and transient episode of muscle weakness accompanied by full conscious awareness, typically triggered by emotions such as laughing, crying, or terror. It is the cardinal symptom of narcolepsy with cataplexy affecting roughly 70% of people who have narcolepsy, and is caused by an autoimmune destruction of the neurotransmitter hypocretin, which regulates arousal and wakefulness. Cataplexy without narcolepsy is rare and the cause is unknown.