This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sleep disorders and eating disorders, Subject name: Psychiatry
True about NREM sleep is 
Select and explain. 
A. Teeth grinding, B. Narcolepsy, C. Night mares, D. Sleep paralysis
A: Teeth grinding
Answer: A: Teeth grinding 
Explanation: Bruxism is seen NREM stage 3, 4. Nightmares, Sleep paralysis are seen in REM sleep. Ref: synopsis of psychiatry, 11e, pg 538.