Shitty answer: Benedryl. The next morning doesn't go well.

Real answer: What you don't do is lay in bed and try to sleep, your mind will just keep going. Do something low impact. Read a magazine or book, nothing that evokes a fear, anger, or excited response. I read social media feeds I have constructed to weed out the ragebait and doomer crap. Mostly tech stuff. I use a red light filter so the screen doesn't keep me going.