@nprofile1q... I usually fall asleep easily but I struggle to fall back asleep after waking up in the middle of the night. I finally found, after so many years of failing, something that works well. It's related to
#4 "the mind". The key is that your "sleep" brain works like flashcards: constantly changing unrelated thoughts. This is very much unlike awake brain that holds lengthy continuous thoughts. So to help your brain get to sleep, make it do flashcards. Specifically: pick a word, any word, then for each letter of the word pick a noun that you can picture in your head. And focus on that picture for a few seconds. Then on to the next letter and word. And on and on.
I got this from a YT vid but I can't find it now sadly.