Try this;

Wake up in the middle of the night, dont move too much.
Just sort of think a few things, maybe do a few math problems in your head, but dont move around alot.
Then after a minute or so, still feeling very tired, slowly get comfortable and start focusing on breathing.
Each exhale makes you feel heavier, focus on that and beleive it. You are focusing on your exhales, each on making you heavier. Pretty soon, you will start to feel a sinking sensation, if you dont, start thinking about it. Sinking down.
Think of your dream, really focus on it, keep telling yourself you are dreaming.

You might hear sounds, i get a very loud sound of wind in my ears, and i feel like im on a massage mat, vibrating all over the place. It sounds a little scary but man, its awesome xD