This may not work for everyone, but what I do is play little games in my head with words, letters and numbers. It occupies my mind and relaxes me, and it seems to just make me doze off. I've got to get in a comfortable position though, which is why it's more difficult to concentrate on trying to get to sleep when it's so hot.
One of my games is you pick a commonly known rhyme, could be a nursery rhyme, a Christmas carol, a saying, a poem, a verse from a song, etc, but it's best not to choose one that's too long, and you need to be able to remember each word. Then you say the song in your head, tapping your foot or whatever body part you feel comfortable (no double-entendre intended), but it's best to tap something you have two of, like your feet for example. The first time, you tap your left foot when you get to words without an A in, then tap your right foot when you do get to words with an A in. If you tap the wrong foot, you have to start again on that letter. Then once you have completed the first rhyme without going wrong with the feet, do the same but with words with a B in, and so on. Example:-
Jingle (left foot)
Bells (left foot)
Jingle (left foot)
Bells (left foot)
Jingle (left foot)
All (right foot)
The (left foot)
Way (right foot)
...and so on. It's a good way to exercise your brain, and can sometimes be enjoyable once you get into it, and it might draw you away from all those annoying thoughts going round in your head, and because it's a little game with hardly no emotion involved, it calms your brain and your nerves, which usually relaxes you and helps to fall asleep. I know my little game I invented may sound odd or might not even work, but I just thought I'd suggest it anyway.
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Female