<prompt> K-complex is seen in which stage of sleep cycle-REMStage 1 NREMStage 2 NREMStage 3 NREM  <response>: Ans. is c i.e., Stage 2 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. 