My depersonalisation went at about 5 yrs post tbi. I wasn't aware I had it for years as my self awareness was nil! I think it's almost a self preservation thing, if you are afraid of what's going on or fear consequences, of can't cope with what's going on. When I reached the point of acceptance and adjusting to fit my limits thing kind of changed without me realising...nothing new there then!
I could sleep standing up, it seemed I was the sleeping martini girl, any time ,anyplace, anywhere! Now my head switches off when overloaded. First thing to go is head to mouth barrier, so I just say whatever is going on in my head. It gets me into much bother.
Hope this helps a little