when I was a kid, I remember what appeared to be me going froma tired waking state directly into a lucid dream, it seemed really odd at the time, I had a dire head ache and was sat on a chair just concentrating on "I want this head ache to go away" then suddenly I was in the dream and knew almost straight away it was a dream as the cupboards had multiplied themselves to a grand scale of like a row of 100 and then ochestral music appeared lol, I thought this must be a dream. haha. Thats my only experience of actually transitioning from wake to sleep in what appeared to be a flash and also realising it was a dream immediately. but it was so odd, the transition between waking and sleeping was flawless haha no black out what so ever, I suppose thats why I remember it from childhood.