Dreaming for Ideas

There's that point around 4 a.m. when I begin to wake where dreams and thoughts begin to overlap. If I can, at a waking moment, channel my thoughts about a manuscript or a character that's giving me trouble, I can often dream a solution.

But the trick is channeling my thoughts in that direction. I don't have very much control about what I think at that hour. Maybe with practice it gets easier?

Are there exercises for that sort of thing?