Which of the following is NOT true of EEG during stage 2 non-REM sleep?

Which of the following is NOT true of EEG during stage 2 non-REM sleep?

• A. There are periods between K complexes or sleep spindles of less than 3 minutes that are unrelated to arousals
• B. Delta activity is less than 20% of the epoch
• C. Abrupt K complex clusters and delta waves may indicate arousals
• D. Activity is high voltage

Answer: (D)

In stage 2 non-REM sleep, the EEG is characterized by brief bursts of specific activity—sleep spindles and K-complexes—set against a relatively low-amplitude background. Delta waves are scarce, typically making up less than 20% of the epoch, and the signal between these bursts remains fairly quiescent rather than highly active. Because of this pattern, EEG activity is not high voltage during stage 2. High-voltage, delta-dominated activity is more characteristic of deeper sleep (slow-wave sleep) where large, high-amplitude waves prevail, or, in other contexts, wakefulness. The other statements fit stage 2: there are short care intervals between spikes and spindles (often under a few minutes) that aren’t arousals, delta activity is limited to under 20% of the epoch, and abrupt K-complex clusters or delta waves can signal arousals.

In stage 2 non-REM sleep, the EEG is characterized by brief bursts of specific activity—sleep spindles and K-complexes—set against a relatively low-amplitude background. Delta waves are scarce, typically making up less than 20% of the epoch, and the signal between these bursts remains fairly quiescent rather than highly active.

Because of this pattern, EEG activity is not high voltage during stage 2. High-voltage, delta-dominated activity is more characteristic of deeper sleep (slow-wave sleep) where large, high-amplitude waves prevail, or, in other contexts, wakefulness. The other statements fit stage 2: there are short care intervals between spikes and spindles (often under a few minutes) that aren’t arousals, delta activity is limited to under 20% of the epoch, and abrupt K-complex clusters or delta waves can signal arousals.