I am only 8 days clean and my thoughts are racing by the time I fall asleep, I wake up around 3am and start thinking about everything. The way I understand it is that addicts use drugs and alcohol to hide their emotional feelings and when coming off of these chemicals you actually start to have "real" feelings and have to learn to cope with them in other ways than drugs and alcohol.
I find that I wake up in the middle of the night and I'll start reading my NA book or AA book, or daily reflections. Just in the hopes that it will bore me so much that I'll fall asleep.