Perhaps meditation? Just sit and pay attention to your breathing. You will have to let go of the thoughts that come to mind many times, and return to breathing. You are not supposed to meditate lying down, because you'll fall asleep.

But in your case, I'd say do what I do, since I also have insomnia: after you get a basic feel for meditation, continue it lying down. Your worry habits may return, but keep focusing on the breath. It's boring. I sleep much better now.

You can read about breathing/mindfulness meditation. It might be boring, but again that can be good.