Stages 3 and 4 of NREM sleep occur
A) every 90 minutes or so throughout the night's sleep.
B) primarily during the first four hours of sleep.
C) primarily during the second four hours of sleep
D) more frequently as the night's sleep progresses.

Question

Quizplus · Accepted Answer

Stages 3 and 4 of NREM sleep, also known as deep sleep, predominantly occur during the first third of the night or the first four hours of sleep. This is when the body undergoes significant physical restoration.

Stages 3 and 4 of NREM Sleep Occur