Relaxation and... At least 30 min before bed write down your to do list for the next day or write out a topic sentence for each thing on your mind. Rank each item by its importance. If there are 8 items then 1 will be #1 & the rest all the way to #8. Review & re-rank until you are done looking at it. If another thing pops in mind write it down. It's key to write them down so they won't swirl in your "monkey mind".
Practice relaxation. Relaxation and imagery techniques can be quite effective for helping people who have trouble falling asleep because of an over active mind. Seeing a therapist for this purpose along with practicing good sleep hygiene can be of great benefit. If still having trouble, as-needed sleep aids can help.