When I was really struggling (schizoaffective) I used to read the back of shampoo / soap bottles.
Because there are complex words that make you slow down, and don't really mean much right away, I found it a great distraction. It might not work for you, but try it!
I have a hypothesis, although I can't prove it at all or find a source proposing the same thing... but the actual science part starts with this:
Neurotransmitters are dependent on certain nutrients. That's why some specialty exclusion diets may help some people (but really, the vitamins are quite pervasive, because we actually do need them).
My idea is that instead of trying to avoid them, what about just using them up before rest/sleep.
On that idea I gave myself permission to revert to my natural dreamy state and work on my writing. Other creative tasks helped me too. Heck, even my chicken breeding project helps use up some mental cookies. Just trying to use my imagination a lot has resulted in a feeling of control and relaxation... that I promise you I didn't use to have.
It may be different for everyone, that's why I hesitate to offer suggestions like this...
But imagine your mind is a boat. You can sit in the back of the boat and hope it will steer itself well so you can relax, or you can go up there and grab the steering wheel thingamy and start telling the boat what to do. Even if it fights you. Even if it's not how you think you should spend your time or what other people would think, etc.