Q: In dream, I do not see myself in mirror and I do not have the waking consciousness. Then how do I know after getting up that it was me in the dream?
A: In fact during the waking state also, without seeing yourself in the mirror, you know about your existence. Just like mind identifies with the physical body during waking state, it identifies with a character in the dream. Since, it is the same mind, this false dream character and the waking character appear to be associated with the same I. It is true that in dream state, you do not have waking consciousness. However, the unconscious mind is the same. So, actually it is the unconscious mind that holds the key to connecting the two. Going a step beyond, various roles are played by the consciousness. The real I is consciousness, pseudo Is can be associated with body, mind etc. Since, consciousness is the same, real I is the same. Life is like a Bollywood movie with one actor (consciousness) playing double roles (body & mind).