This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous System, Subject name: Physiology
K - complex and sleep spindles are seen in which stage of sleep 
Select and explain. 
A. REM, B. Stage 1 NREM, C. Stage 2 NREM, D. Stage 3 NREM
C: Stage 2 NREM
Answer: C: Stage 2 NREM 
Explanation: Ans. (c) Stage 2 NREM(Ref: Ganong, 25th ed/p.273)Stage 2 NREMWaves with frequency 12-14Hz called sleep spindles seenhigh voltage biphasic waves called K complexes also seen