I know everyone gets tired of hearing this... but sometimes you just have to let it go, somehow someway. you don't have to force yourself to let it go forever, I don't try resolve the issue if I'm in bed. Sometimes it helps to write and down and then say to yourself "I'll think about this tomorrow."

Listening to relaxing music helps, or right something that's fun and interesting. I don't find reading self help books at bedtime helpful.