From what stage of sleep are people typically most difficult to arouse?
A) NREM,alpha waves
B) NREM,sleep spindles
C) NREM,delta waves
D) REM

Question

Quizplus · Accepted Answer

NREM sleep is typically divided into three stages, with Stage 3 being characterized by the presence of delta waves. This is also known as slow-wave sleep, and it is during this stage that people are most deeply asleep and difficult to arouse.

From What Stage of Sleep Are People Typically Most Difficult