Here's a tip for falling asleep. I don't think you'll see it anywhere else. It goes like this: Don't think words.
By that I mean don't imagine conversations that you plan to have, and don't replay in your head conversations you've had.
It's impossible to clear your mind of all thoughts. But I find it somewhat easy to switch off the language center of my brain. What happens after that is a flow of images, starting with ones that make some sense to my current life, quickly followed by randomness, then sleep. It usually takes less than a minute.
Let's say something is bugging you, or fascinating you, and the thought is keeping you awake. I'll bet that in those situations you're obsessed with the verbal elements of your problem. You're imagining what you will say to someone, or how you will explain yourself, or maybe what words someone else chose when annoying you. To fall asleep, don't abandon the troublesome topic, because you probably can't. Just picture the situation in images alone. That will satisfy the part of you that can't let go of the problem while putting you on the sleep trajectory.
To be fair, I have no idea if this method will work for you. It's just something I discovered that works for me.
My wife hates my ability to sleep just about anywhere. Yesterday I dropped off for a few minutes during the new movie Paul. I would have awakened in ten minutes on my own, refreshed and ready to drive home. But that plan went off the rails when Shelly decided it would be funny to slap me in the chest and see what I would do if I woke up suddenly to a loud action sequence in the movie. I'm told it was hilarious.
Anyway, if you try my sleep tip, let me know if it works for you.