Which of the following statements describes a unique characteristic of stage 2 of non-REM sleep?

• A. Delta waves dominate the EEG during stage 2 of non-REM sleep.
• B. Sleep spindles and K-complexes are prominent features during stage 2 of non-REM sleep.
• C. Muscle tone is completely lost during stage 2 of non-REM sleep.
• D. Rapid eye movements are frequently observed in stage 2 of non-REM sleep.

Answer: (B)

Verified step by step guidance

1. Understand that non-REM sleep is divided into multiple stages, each with distinct EEG patterns and physiological characteristics.
2. Recall that stage 1 of non-REM sleep is characterized by theta waves, and stage 3 (and 4) are dominated by delta waves, which are slow-wave sleep.
3. Identify that stage 2 of non-REM sleep is uniquely marked by the presence of sleep spindles and K-complexes on the EEG, which are brief bursts of brain activity.
4. Note that muscle tone is reduced but not completely lost during stage 2, and rapid eye movements are characteristic of REM sleep, not stage 2 of non-REM sleep.
5. Conclude that the statement about sleep spindles and K-complexes best describes the unique features of stage 2 of non-REM sleep.