What is another term for REM sleep?

REM sleep, or Rapid Eye Movement sleep, is often referred to as active sleep. This is because during this phase of sleep, brain activity resembles that of wakefulness, and physiological changes such as rapid eye movements, increased heart rate, and irregular breathing occur. It is during REM sleep that most dreaming takes place, indicating a high level of brain activity. The term "active sleep" captures this energetic and dynamic state of the brain, differentiating it from other sleep stages that are characterized by more subdued brain activity and physical relaxation. In contrast, slow-wave sleep, deep sleep, and quiet sleep refer to stages of sleep where the brain is less active and the body is more relaxed.