Which statement best describes changes from stage N2 to stage N3 sleep?

Which statement best describes changes from stage N2 to stage N3 sleep?

• A. Sleep spindles may persist into stage N3 sleep
• B. Delta activity is minimal in N3
• C. Eye movements are prominent in N3
• D. Chin EMG activity increases compared to N2

Answer: (A)

As you move from lighter non-REM sleep into deeper non-REM sleep, the brain shifts from characteristic N2 patterns toward a delta-dominated profile. Sleep spindles are a hallmark of N2, but as the sleeper transitions into deeper sleep, some spindle activity can still be seen briefly into early N3. That overlap is what this statement captures. In contrast, true N3 sleep is defined by predominant delta activity, so saying delta activity is minimal in N3 is inaccurate. Eye movements are typically minimal in deep non-REM sleep, not prominent, and chin EMG tone tends to decrease rather than increase as you deepen into N3.

As you move from lighter non-REM sleep into deeper non-REM sleep, the brain shifts from characteristic N2 patterns toward a delta-dominated profile. Sleep spindles are a hallmark of N2, but as the sleeper transitions into deeper sleep, some spindle activity can still be seen briefly into early N3. That overlap is what this statement captures.

In contrast, true N3 sleep is defined by predominant delta activity, so saying delta activity is minimal in N3 is inaccurate. Eye movements are typically minimal in deep non-REM sleep, not prominent, and chin EMG tone tends to decrease rather than increase as you deepen into N3.