Ok my mom told me this:

When you are in bed look up, then close your eyes so that while your eyes are closed they are still looking up. And leave them like that. (Looking up produces serotonin, or some other chemical, I forgot what she said).

Then count from 100 down to 1 while imagining yourself descending down a flight of stairs.

Do this for 10 days. After 10 days only count from 50 down to 1. Repeat this 10 days. Then when those 10 days pass, count only from 25 down to 1.

The goal here is that eventually you program yourself to fall asleep after counting down from 10. It takes 40 days in all.

By the way I tried this last night (the night before I had trouble falling asleep). I kept my eyes up (which felt a little uncomfortable since I wasn't used to it, but then i adjusted). After I counted 100 down to 1 I felt relaxed. After a few miutes I turned to my side (with my eyes still up). And then I fell asleep after a short while.