When I can't sleep I sometimes do number meditation. I was taught it at a long time ago yoga class..
It goes like this - you count from 1 to 100 and from 100 to 1 at the same time.
Hence; 1-99. 2-98. 3-97. 4-96. 5-95 etc etc.
I usually only get to 25/75 before I go to sleep.