This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
NREM Sleep true is ? 
Select and explain. 
A. Teeth grinding, B. Narcolepsy, C. Nightmares, D. Sleep paralysis
A: Teeth grinding
Answer: A: Teeth grinding 
Explanation: Ans. A. Teeth grindingSlow wave sleep (stage 3 & 4 of NREM sleep) disorders r Sleep walking (somnambulism), night terror (sleep terror or pavornocturnus), Nocturnal enuresis, Bruxism (teeth grinning), and sleep talking (somniloquy).REM sleep events/disorder:- Nightmares, nocturnal penile tumescence, Narcolepsy.