Well, you are growing overnight. That is, if you haven't reached your fullest potential.
Because overnight you are lying down, and gravity does not have a "compression" effect on your body (Your spine). Because of this, your spine will slightly "spring" back and when you wake up, you...
Human hair can not grow visibly longer overnight, sorry.
0.1 milimeter (approx.)
honestlt i believe from 1/2 of a inch to 1 inch
you can't you would need help from future medicine