#4 Your Brain Activity Increases When You Sleep
When brain waves are monitored while people are sleeping, distinct patterns for each stage of sleep are visible. Brain signals slow down greatly during the early stages of non-REM sleep, although there are a lot of short bursts of activity during Stages 2 and 3.
Brain activity increases and changes its waveforms noticeably during REM sleep. The reason REM sleep is considered the state most strongly linked with vivid dreaming is because of increased brain activity.
In the REM stage, you experience daytime levels of blood pressure, breathing, body temperature, pulse, and body heat. The sympathetic nervous system, which supports automatic reactions like “fight or flight,” becomes exceedingly active. Your body, however, is completely motionless.