Final answer:
Atonia is exhibited in REM sleep. During REM sleep, the body experiences muscle paralysis, except for the muscles responsible for respiration and circulation. This stage is also associated with dreaming.
Step-by-step explanation:
Atonia is exhibited in REM sleep. REM sleep is characterized by rapid movements of the eyes and high brain activity. During REM sleep, the body experiences muscle paralysis, known as atonia, except for the muscles responsible for respiration and circulation. This stage of sleep is also associated with dreaming.