Which feature is typical of REM sleep?

• A. Muscle atonia
• B. Increased muscle tone
• C. Sleepwalking
• D. Absence of dreams

Answer: (A)

REM sleep involves rapid eye movements with high brain activity, but the body experiences muscle atonia—essentially a temporary paralysis of most skeletal muscles. This prevents acting out dreams, which are common during REM. Activities like sleepwalking happen during non-REM sleep when muscle tone isn’t suppressed, so they aren’t typical of REM. Increased muscle tone isn’t a feature of REM sleep, and while some people don’t recall their dreams, dreaming itself is typical of this stage, not the absence of it.