During this slow wave sleep, the brain emits slow delta waves and somnambulism is most likely to occur:

• A. REM sleep
• B. NREM stage 1
• C. NREM stage 2
• D. NREM stage 3

Answer: (D)

Slow-wave sleep is the deepest stage of non-REM sleep, marked by slow, high-amplitude delta waves on EEG. In this stage, the brain is less responsive to outside stimuli, yet partial arousals can still occur. Somnambulism, or sleepwalking, is a parasomnia that most often arises during this deep NREM sleep when a person is not fully awake but not fully asleep either. REM sleep, by contrast, involves rapid eye movements, more brain activity, and muscle atonia that prevents movement, so sleepwalking is unlikely then. So the scenario described points to non-REM stage 3 as the most likely time for somnambulism.