Which of the following best describes REM sleep?

REM sleep, or Rapid Eye Movement sleep, is indeed characterized by the presence of rapid movements of the eyes, which is a defining feature of this sleep stage. During REM sleep, brain activity becomes more similar to that of wakefulness, and most of the vivid dreaming occurs during this phase. The brain shows a high level of activity, and this is when the body experiences atonia, or a temporary paralysis of most voluntary muscles, which prevents the acting out of dreams. This stage is crucial for cognitive functions such as memory consolidation, learning, and emotional regulation.

By contrast, the other options do not accurately define REM sleep. Non-dreaming sleep typically refers to non-REM sleep stages, where dreaming is less common. Deep sleep, which is characterized by slow-wave activity, is associated with restorative processes and does not feature the eye movements associated with REM. Light sleep with minimal brain activity often corresponds to the early stages of sleep or non-REM sleep, rather than the more active state during REM. Therefore, the description highlighting rapid eye movement is the most accurate and specific for defining REM sleep.