Don't laugh. When I can't sleep and my mind won't settle down, I sing to myself. Just the words running though my head - I'm not actually singing. But concentrating on the words makes all those other thoughts go away. I 'sing' whatever comes to mind. Sometimes hymns, sometimes childrens' songs. And I usually sing the same song over and over.
This works 95% of the time. It doesn't work so well when I'm really anxious about something. Then I try an OTC.