This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sleep Disorders, Subject name: Psychiatry
Cataplexy is characterized by? 
Select and explain. 
A. Hypnopompic hallucinations, B. Nocturnal penile tumescence, C. Decreased muscle tone, D. Somnambulism
C: Decreased muscle tone
Answer: C: Decreased muscle tone 
Explanation: Ans. is 'c' i.e., Decreased muscle tone * Cataplexy is the most common accessory symptom of Narcolepsy and is characterized by sudden decrease in muscle tone, either, local or generalized.