AP PSYCHOLOGY

Detailed explanation-1: -Rapid eye movement (REM) sleep, or stage R, usually starts about 90 minutes after you fall asleep. Brain activity increases, your eyes dart around quickly, and your pulse, blood pressure, and breathing speed up. This is also when you do most of your dreaming.

Detailed explanation-2: -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-3: -While your brain is aroused with mental activities during REM sleep, the fourth stage of sleep, your voluntary muscles become immobilized. Your brain also uses this time to cement information into memory, making it an important stage for learning.

Detailed explanation-4: -REM sleep happens about an hour to an hour and a half after falling asleep. REM sleep is when you tend to have vivid dreams.

Detailed explanation-5: -See Full Reference . Each cycle through all the sleep stages takes 90 to 120 minutes to complete. With each new cycle, you spend increasing amounts of time in REM sleep, with most of your REM sleep taking place in the second half of the night.