I set what I call "totems," things that stay constant even when everything else changes. For instance, I'll set one day of the week as being completely off limits to work. Work me the other 6 days, but this one is mine.

Another totem I have, is to make my breaks/lunches non-work affairs. If I have a book I want to read or just surf Facebook, I do it during that time.

That's how I stay sane in jobs like that. I have others depending on the job, but those are my two big ones. I'm looking to get into the criminal justice field, so I can safely say irregular hours will be my bread and butter as well.