Which of the following is true of human sleep cycles?
A) Sleep cycles are random across the night.
B) Subjects first enter REM sleep and then transition to non-REM sleep.
C) As the night goes on, the relative length of REM sleep increases in each successive cycle.
D) Stage 3 of slow-wave sleep mostly occurs in the early morning hours.
E) Each non-REM/REM cycle lasts about 45 minutes.

Question

Quizplus · Accepted Answer

As the night progresses, the relative length of REM sleep increases in each successive cycle. This means that the first cycle of sleep has the least amount of REM sleep, while the last cycle before waking up has the most amount of REM sleep.

Answer: E
 Each non-REM/REM cycle lasts about 90 minutes on average, and includes approximately 5 stages of sleep. The first cycle may be shorter or longer than this, but subsequent cycles generally follow this pattern.

Which of the Following Is True of Human Sleep Cycles