|MadSci Network: Anatomy|
Hello, Cody. The main reason you're taller in the morning than at night is due to the force of gravity. You see, all day long gravity pushes down on our vertebrae, pushing water out from between our spinal disks. All this pressure can cause us to lose up to an inch off of our height during the day. At night, the water diffuses back between our disks, elongating us once again. Of course, since we are in a horizontal position, the force of gravity will not affect us negatively. Hope that helps, Peter Bosani.
Try the links in the MadSci Library for more information on Anatomy.