I used to have Derealization. What I used to get was constant tunnel vision, feeling of unreal, I thought I was getting messages sent to me from the media and lots more. What I did that cured it was started Karate. After about 2 months of doing Karate I just realized all of a sudden that i no longer have it. Yes it is a scary feeling being in that kind of situation with Deralization but you just have to do something like a sport.