Medical Specialties: Internal medicine, Neurology

Clinical Definition

Cataplexy is an acute, transient attack characterized by hypertonia and weakness. Weakness can be generalized or limited to certain muscle groups. Precipitating factors associated with cataplexy are intense emotional stimuli, such as anger and fear.


A decrease in hypocretin, which is a neurotransmitter, is believed to be a contributing factor to cataplexy. Cataplexy is also often associated with the sleep disorder narcolepsy. 

In Our Own Words

Sometimes confused with epilepsy, cataplexy is the sudden and temporary loss of muscle tone. When it occurs, the individual has full awareness and consciousness. The face, neck and knees often become weak, sometimes severe enough to lead to physical falls or temporary paralysis. It usually goes away in under two minutes.


Cataplexy is often a symptom of narcolepsy, which is a sleep disorder. Strong emotions, such as laughter, fear, anger or surprise tend to trigger events. There also appears to be a connection between a decrease in a chemical in the brain called hypocretin and cataplexy and narcolepsy. 

Relevant Conditions
Side Effects
  • Loss of muscle tone
  • Weakness
Share this article
  • National Niemann-Pick Disease Foundation. “What is Cataplexy?” Accessed November 2013.
  • Sources for Other Sections: Sleep Disorders Guide. Cataplexy. Accessed November 2013.
  • University of Maryland Medical Center. Narcolepsy. Accessed November 2013.
  • Stanford School of Medicine. About Narcolepsy. Accessed November 2013.
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