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
Theta waves are seen in- 
Select and explain. 
A. Stage 1 REM, B. Stage 2 REM, C. Stage 1 NREM, D. Stage 2 NREM
C: Stage 1 NREM
Answer: C: Stage 1 NREM 
Explanation: Ans. is 'c' i.e., Stage 1 NREM * Full awake and alert state - Beta rhythm* Awake, eye closed and mind wandering but with less attentiveness - Alpha - rhythm* Stage 1 NREM - Theta rhythm* Stage 2 NREM - Sleep spindles, K complex* Stage 3 & 4 NREM (Deep sleep) - Delta rhythm* REM sleep - Beta rhythm and sometimes also reappearance of alpha rhythm.