Well, I never heard myself snore. I have been told that I do, though
I remember that one one single occasion I actually "consciously" noticed the moment of falling asleep, of changing from conscious thoughts to the dreamworld. I have never had that again, but I remember it quite an interesting experience.
Usually I will start nodding off a little and quickly realize that I better go to bed. I think I only actually fell asleep in front of the TV once.