Arousal is most difficult in which stage of sleep -: (A) Stage 1 NREM, (B) Stage 2 NREM, (C) Stage 3,4 NREM, (D) REM
Answer is C. Ans is 'c' i.e., Stage 3,4 NREM'In general, the ease of arousal from sleep parallels the ordering of the sleep stages, with NEM and stage 1 being the easiest for arousal and stage 4 the most difficult.