I go a little bit more meta, and start imagining myself sleeping.

Kind of… say I’m part of the Start Trek crew. I imagine how would it be to sleep in the Enterprise. How is the room? What furniture is there? Is there a window/screen showing the outside? Etc…

For me, works wonderfully.

My own experience is that if I think something needs to be acted on, and it’s very quick or very urgent, I just do it and go back to bed. If it’s neither, I write it down. I find either of those to be easier than trying to sleep with the endless nagging by the back of my brain.