Other causes for dissociation?

For almost 5 months now, I have felt what I now know to be depersonalization and derealization. I understand that this is caused by anxiety and panic attacks. However, the more information I gain on anxiety, the less I think that's what actually going on with me. A couple of nights when I've stayed up late, I feel myself getting really scared. However, I have never thought I was going to have a heart attack, and usually I'm not scared of actually dying or death. I feel more scared of... fear itself, if that makes sense? And also, it feels someone moved everything around me in the wrong place, like someones messing with me. I always feel like someone is in my house and watching me and laughing at me because I'm afriad. I also have a huge fear of windows and clear doors, again like, someone is watching me. I always feel weird if I'm not fully clothed (in long pants and a sweatshirt) or if I stand in an open place. Maybe it's paranoia? But anyways, I was wondering if anxiety is the only thing that causes dissociation. Because I always feel like I'm not real, and dead, and invisable so people don't even notice I'm there, but I rarely feel "anxious" and when I do it's not of heart attacks/death. I'd be very thankful if anyone knew anything..