Cataplexy: A debilitating condition in which a person suddenly feels weak and collapses at times of strong emotion such as during laughter, anger, fear, or surprise. In so collapsing, people with cataplexy may injure themselves. For example, laughter and other emotions may trigger a reflex that can bring many of the muscles of the body to the point of collapse. Cataplexy often affects people who have narcolepsy.
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