I'd like to add to the part about becoming disengaged and becoming less of an outgoing person: I just went through this and didn't realize it. I went from hanging out with friends all the time to barely at all and even thinking of excuses to skip family gatherings. I've skipped weddings (granted, people that can be described as "acquaintances" at best). I blamed night shift, I blamed the 12 hours days. I cursed the 12 hour days while constantly being thankful for it (I only work 1 out 2 weeks).

You need to force yourself to not let this happen. Pick a day to go out. Pick once a month at least to hang out with friends. Pick up an additional hobby that can't be done from inside your home.

It's hard. Your work becomes your life and none of your friends will understand your struggle. You will slowly start to grow disdain for the general public and your patience for people you don't know will wear thin.

I used to be a very social, but submissive person. I hated confrontation and would rather let people walk all over me than stand up for myself. While I'm still considered nice and kind of a push over at work, my family (one in particular) needed time to adjust to the change. They couldn't handle me sticking up for myself or not having the patience for people who couldn't consider others. I feel it was a positive change, but it was a drastic change for me nonetheless. That person who couldn't handle it was my sister, my best friend up until recently. It's a bridge that has been burned and I don't believe will ever be rebuilt.

You're encouraged to "turn it off" when you get off shift. It's damn near impossible. I'm lucky to have a father that works on the streets for the same department. I have him to confide in outside of work. My SO doesn't understand the fire in me that ignites when someone says to "just send the damn ambulance and quit asking questions!" He understands that I may get upset or have bad days, and I'm damned lucky that he humors me in it all. But he doesn't get it, which I don't expect him to.