What does cataplexy refer to?

Cataplexy is characterized by sudden and brief episodes of muscle weakness or paralysis that occur while a person is awake. These episodes can be triggered by strong emotions such as laughter, excitement, or anger, and they can lead to a complete loss of muscle tone, sometimes causing the individual to collapse or fall. This phenomenon is associated with narcolepsy, a sleep disorder that includes excessive daytime sleepiness and the sudden onset of sleep.

The other conditions described do not accurately represent cataplexy. The sudden urge to fall asleep relates to the overwhelming sleepiness experienced in narcolepsy but does not involve paralysis. Paralysis during REM sleep pertains to the normal loss of muscle tone that prevents individuals from acting out their dreams, which is not what occurs during waking. The inability to move upon waking describes sleep paralysis, which happens when a person temporarily experiences an inability to move or speak while falling asleep or waking up, and is also distinct from cataplexy.