AP PSYCHOLOGY

Detailed explanation-1: -Stage 4: REM sleep In REM sleep, your brain waves and eye movements increase. Your heart rate and breathing also speed up. Dreaming often happens during REM sleep. Your brain also processes information during this stage, making it important for learning and memory.

Detailed explanation-2: -These four sleep stages are called non-rapid eye movement (non-REM) sleep, and its most prominent feature is the slow-wave (stage IV) sleep. It is most difficult to awaken people from slow-wave sleep; hence it is considered to be the deepest stage of sleep.

Detailed explanation-3: -There are four sleep stages, including one for rapid eye movement (REM) sleep and three that form non-REM (NREM) sleep. These stages are determined based on an analysis of brain activity during sleep, which shows distinct patterns that characterize each stage.

Detailed explanation-4: -The human body cycles through two phases of sleep, (1) rapid eye movement (REM) and (2) non-rapid eye movement (NREM) sleep, which is further divided into three stages, N1-N3. Each phase and stage of sleep includes variations in muscle tone, brain wave patterns, and eye movements.