This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Higher Functions, Subject name: Physiology
Delta waves are seen in: 
Select and explain. 
A. Deep sleep, B. REM sleep, C. Awake state, D. Stage II nREM sleep
A: Deep sleep
Answer: A: Deep sleep 
Explanation: REM sleep is characterized by b waves, the waves actually of ale wakefulness. Hence, REM sleep is also called "paradoxical sleep". Awake state with eyes closed - a waves; with eyes open - b waves. NREM sleep: stage 1 shows periodic sho bursts of a waves.