Depending on your sleeping position sleeping can vary on the frame of mind your in also. On my back, thinking usually occupies my mind, the fetal positionalways brings upon the drowzy stage of sleep.

If you just let your mind wonder, it almost like switching off the thoughts and letting the subcon take control, hat helps get me to sleep.
Otherwise im not sure what will work. But i do know, that the more you think of wanting to dream that night and stuff, the more awake your conscience is.