"Counting really slowly with the goal of reaching 150 is a decent way to fall asleep. If you have any thoughts during it just let them play out, and if you forget what number you're on just go from what you last remember. If you make any major movements just start again.
The goal is to force your brain in to slowing down and not having any jerky motions or thoughts, and eventually reaching such a level of carelessness that you eventually fall asleep without realising. Helped me quite a few times, especially with rain sounds, hope it helps some of you too!"