Which statement is NOT a described feature of REM sleep?

Which statement is NOT a described feature of REM sleep?

• A. Rapid eye movements
• B. Substantial delta waves
• C. EEG similar to wakefulness
• D. Muscle atonia

Answer: (B)

REM sleep features rapid eye movements, near-total muscle atonia, and an EEG that looks desynchronized and wake-like (low-amplitude, mixed-frequency activity). Substantial delta waves are not part of REM; those slow, high-amplitude waves occur in deep non-REM sleep. So the presence of delta waves does not describe REM sleep, making that statement the not-described feature. The rapid eye movements and muscle atonia are characteristic of REM, and the wake-like EEG is also typical, which contrasts with the delta-dominant activity seen in deep sleep.

REM sleep features rapid eye movements, near-total muscle atonia, and an EEG that looks desynchronized and wake-like (low-amplitude, mixed-frequency activity). Substantial delta waves are not part of REM; those slow, high-amplitude waves occur in deep non-REM sleep. So the presence of delta waves does not describe REM sleep, making that statement the not-described feature. The rapid eye movements and muscle atonia are characteristic of REM, and the wake-like EEG is also typical, which contrasts with the delta-dominant activity seen in deep sleep.