Answer
After Marvin settled down to sleep the following experiences in the indicated stages of sleep:
Marvin settled down to sleep passing through stages 1-3 of NREM sleep
1 . Sleep walking occurred in stage 4 ( slow wave ) of sleep.This is the deepest stage of sleep so his mother was able to return him to his bed without awakening him when he was in stage 4.
Work Step by Step
Marvin continued to cycle through REM and NREM sleep.
2. Dreaming occurs in REM sleep
The noise of the alarm clock was the sensory stimulus that awakened him.
The auditory stimulus triggered his reticular activating system (RAS). The Ras then sent stimuli to the cerebral cortex by way of the thalamus. The result was an enhanced state of arousal which culminated in wakefulness.
