Each cycle of sleep during a typical night tends to be about
A) 5 minutes long.
B) 20 minutes long.
C) 35 minutes long.
D) 90 minutes long.
E) 140 minutes long.

Question

Quizplus · Accepted Answer

Each cycle of sleep during a typical night tends to be about 90 minutes long, consisting of four stages of non-REM sleep followed by a period of REM sleep. This cycle repeats several times throughout the night.

Each Cycle of Sleep During a Typical Night Tends to Be