It defiantly takes the right person to work night shifts. I have a friend who is a nurse but she's a night owl, she always stayed up at night and was late to class everyday when we were in school
So the night shift was natural to her. I don't think I could have done it.
Leaving co-workers is hard, you never know what type of new environment you might walk in to. It may be better pay or closer to home but what is your stress gonna be like? Hard choice, but I would never stay completely decided to a particular hospital, company, practice because the hard truth is, no matter how hard, long you worked for someone and dedicated yourself to them, the facility, the pts etc. that you are replaceable and that is the way they will treat you. Not that they don't appreciate you but it's just the honest truth. You have to do what's best for YOU. Good luck!