Final answer:
The most active brain areas responsible for visual and auditory processing are during REM sleep, wherein brain wave patterns are similar to those when awake and dreaming is most frequent.
Step-by-step explanation:
The visual and auditory areas of the brain are the most active during REM sleep. During REM sleep, brain waves resemble those observed while a person is awake. This stage of sleep is characterized by rapid eye movement, and it's the period when dreaming most commonly occurs.
Furthermore, research has shown that during REM sleep, there is an absence of muscle tone, but a high level of brain activity, contrasting the low frequency, high amplitude delta waves of stage 3 sleep in the NREM phase. Additionally, advanced imaging techniques like fMRI have been utilized to detect and categorize brain activity during REM sleep, assisting in the exploration of dreaming.