The dragon constructed it can be sent to others to show up in their dreams. This I have verified several times. It can also happen that one, so they say, falls asleep. Awareness simply disappears and the body is lax. I have not done this lately, I am into other things.
Distance makes no difference.
I seldom discuss this kind of thing as it renders most people scared, as they say, to have such awesome powers. It does not feel awesome to me, somewat scary on occasion and it produces a high sense of responsibility. For those who wish to test or verify, no thanks, I am not a performing monkey. Find someone else. A crude simplification is that the mystical lacks form, the astral has only form and the material is impenetrant.