Sorry, but people do have the right to walk around their own apartment, any time of the day or night. It's not like they are playing loud music at that hour, or bowling, they are just walking. You can't blame them if the floors creak.
For crying out loud, just put in earplugs.
I used to work a 4-12 shift, and get home around 1am every morning. My downstairs neighbor, like you, pitched a fit, because I walked ( in my socks!) across my own goddang floors! Well, fine, I don't have to tip toe across my own floor. I was trying to be quiet out of courtesy before, but once he complained? I stomp across the floor in my work boots when I come home now, and sit and watch some tv, too.