Beta brain waves are the cause of the yama-yama'ing that continues when we want to sleep. Try a routine before going to bed... telling the body and brain that soon it will be time to sleep. Try making a list of those things left undone, so you won't feel like you have to keep them in mind to remember them.

Meditation will help you to utilize Alpha and maybe in the future, theta brain waves... allowing you to tune out and remove those horrible thoughts that keep you from sleeping. ((I personally use a delta wave CD from my T.)