If your problem is that you can't get your brain to "turn off", try getting up and get a piece of paper and pen and WRITE DOWN whatever is whirling around in your brain.
What this does, is you see physically that it is being listed and you won't have to worry about forgetting it if you fall asleep, so it leaves you free to go ahead and sleep! Works for me, jespecially when we have big projects going on that keep me occupied thinking of all the little things that must be done.
Heidi