hypothesis: two techniques to help train the mind to enter both of these states, are:
- practice really doubting whether "reality" is real
- practice really believing a non "real" thing (faith)
anecdote: I had a dream last night. Inside the dream there was some point where I was doing something precarious — I forget what — and later, still inside the dream, I thought "man, it's good I didn't doubt whether I was dreaming at that precarious point, because I might have fallen.. but wait, maybe I was dreaming at that point.."