Cataplexy

Cataplexy refers to sudden, brief and transient episodes of muscle weakness accompanied by both total conscious awareness and bouts of emotion such as laughter, terror, crying, etc. Approximately 70% of people diagnosed with narcolepsy also have episodes of cataplexy. It is believed to be caused by an autoimmune destruction of the neurotransmitter hypocretin, which regulates arousal and wakefulness. Cataplexy, without associated narcolepsy is rare, but does exist.