Winter argues that once you’re physically relaxed, if you get “your mind clear of any active thoughts for just ten seconds, you will be asleep.” The key to falling asleep quick is thus to stop the train of thoughts that is usually rumbling through your head. You have to stop ruminating on the regrets, worries, and problems of the day.
‒ https://www.artofmanliness.com/health-fitness/health/fall-asleep-fast/