I don't have DID but in my dream I did; I went from being almost undressed and ready for a nice refreshing shower to standing in front of my closet in multiple layers of clothes and realizing what had happened (that I had "lost" time) and being anxious and frustrated. I had really been looking forward to the shower and now I still had more clothes to take off!

I've dreamed I've fallen asleep while dreaming before and my T said that wasn't real good because it is sort of a double negative, avoiding being awake/alive/aware even when you're asleep! But I can't imagine what dissociating while I'm asleep (and dreaming weird things to begin with :-) might mean.

One thing my T helped me with with dreams was to realize that, as with therapy, it can be helpful to go with the feelings in dreams rather than just the images/what happens. The feeling of anxiety and frustration when I realized I had dissociated and had done it previously in that world, does help me understand a little better what my unconscious was trying to get across to me but the feelings have also "stuck" a bit now that I'm awake.