On a couple of occasions I've tried "lucid dreaming". I imagine myself in a tunnel and I find a hole in the ground and descend down, down, down into the dark by

On a couple of occasions I've tried "lucid dreaming". I imagine myself in a tunnel and I find a hole in the ground and descend down, down, down into the dark by a rope, and sometimes my mind will make some interesting things happen. Sometimes I'll just fall asleep :-)