Which sleep stage is characterized by rapid eye movements and vivid dreams?

• A. Somnambulism
• B. Sleep apnea
• C. Detoxification
• D. REM sleep

Answer: (D)

REM sleep is the stage characterized by rapid eye movements and vivid dreams. In this phase, the eyes move quickly under the eyelids, brain activity ramps up to levels similar to wakefulness, and dreaming is most vivid and frequent. The body also experiences atonia, a temporary paralysis of most active muscles, which helps prevent acting out dreams. REM sleep cycles several times each night, becoming more prominent in the later portions of the night.

The other options don’t fit the description: somnambulism (sleepwalking) happens during non-REM sleep, not during the dream-rich REM phase; sleep apnea is a breathing disorder interrupting sleep, not a sleep stage; detoxification is not a sleep stage at all.