Riddle me this!

Getting your body to move around increases your heart rate spreading oxygenated blood all over your body and causing you to breathe more to aborb more oxygen. Also with your environment moving because your walking it adds to the stimulus triggers your brain has to comprehend. Like distance to objects around you so you need to be mentally awake to maneuver around on 2 feet. Also as your laying there your body preps for sleep paralysis releasing hormones into your blody slowing down your processes. When you stand up you rest all that.