To dissociate means to seperate, detach, withdraw to avoid a traumatic situation. Depersonalization is more the out of body experience where you are seeing yourself doing things.

I had a similar experience once before. I lied down to sleep, but I never went to sleep. I felt like I was disembodied and saw that I was in a house with 20 people or more. We made small talk, but I wasn't to involved because they were gathered amongst themselves drinking and laughing. I was a little disturbed. I tried to get up but my body was rigid, like I was being held there. We were all in a dark room where we lived. I said "Hey, let's go in the kitchen", then there was a lit kitchen, so we moved in there. I then started making them all rooms which they can do what they want in it. Was it a dream? It didn't feel like one. Some how I feel that I might have been interacting with the other alters. I wasn't exactly too accepting at that point, but I'm now a lot better for it.