Which of the following best describes REM sleep?

Sleep in which the brain becomes more active but muscle activity is blocked.

Explanation:

The brain cycles through five distinct phases during sleep: stages 1, 2, 3, 4, and rapid eye movement (REM) sleep. REM sleep makes up about 25% of your sleep cycle and first occurs about 70 to 90 minutes after you fall asleep. Because your sleep cycle repeats, you enter REM sleep several times during the night.

During REM sleep, your brain and body are energized and dreaming occurs. REM is thought to be involved in the process of storing memories, learning, and balancing your mood. REM sleep begins in response to signals sent to and from different regions of the brain. Signals are sent to the brain's cerebral cortex, which is responsible for learning, thinking, and organizing information.