Why do i wake up in the middle of the night with my feet feeling like they are really dry?

The problem is two fold. First you are dehydrated. You should drink 4 8oz. glasses of water immediately before you go to bed. Second, your skin is not being moisturised properly. You should rub Vaseline all over your feet just before you go to bed too. Don't rub it off before you get into bed though. I know it is messy, but it should help with your problem.