what happens during rem sleep

During REM (Rapid Eye Movement) sleep, your eyes move rapidly behind your closed eyes, your heart rate speeds up, and your breathing becomes irregular. This stage of sleep is associated with dreaming and memory consolidation. In contrast to other stages of sleep, in which your brain waves slow down, your brain is highly active during REM sleep, and your brain waves become more variable. During REM sleep, your brain activity looks very similar to brain activity while you’re awake. Your muscles normally become limp to prevent you from acting out your dreams. REM sleep makes up about 25% of your total time asleep, and it usually happens 90 minutes after you fall asleep. The first period of REM typically lasts 10 minutes, and each of your later REM stages gets longer, and the final one may last up to an hour.