I don't try to control thoughts, I either just keep bringing them back to something "I" want to think about or I get busy/engrossed in doing something that takes a lot of attention and that I find more interesting. The middle of the night can be hard for me though since I'm "captive" in bed. If I have trouble for too long though, I get up and go downstairs and immerse myself in a book or project for awhile so when I get more tired I can go back to bed and have something to continue thinking about while I fall back asleep.