I think I can relate to what you wrote. Reality seems to become less real to me at those times....maybe not less real, but more like fake or false as in a fading dream. If I close my eyes at those times, I can even forget the world and myself, and I can be surprised by what I see when I open them. As for what you mentioned about not feeling that your mind ends somewhere, I get that as well, but it is a dangerous thing for me, as it can lead me to suicidal thinking, because I start to "understand" that this "reality" is just a pinpoint that has trapped my mind into thinking this is where it should be, when there is so much "being" that can be experienced if I were to shake this mortal coil my mind has thought up. So....when I start to feel these thoughts coming on, or the preceding depersonalization, I work up a very light mania - talking, clapping, walking, something to focus on in the "here and now" and I can sometimes keep it at bay.