kcat220, maybe the reason you are able to get into SP with your window open and the light shining on you is because it causes you to sleep "lighter".

As for your lower body getting stuck.. try rolling to your left or right until you're off the bed.. or try feeling yourself sink through your bed until you hit the floor.. or try picturing the wall in your room with you standing next to it and feeling its texture (if you concentrate on this deeply enough you may be able to project yourself there).