When I can't go to sleep, I count. I've gotten up to ~1,000! When that really isn't working, I'll do deep breathing exercises. I'd recommend both!
Hey Ame, Counting is generally the most common tactic for when you cannot go to sleep. This is because it is a common, thoughtless action that sets up a pattern for your brain, sort of like your own personally generated metronome. T
I notice you saying you have gotten up to 1000 before. A few times by the suggestion. My advice is to count backward. The counting remains as a mundane task, however your brain is not accustomed to counting backward from large numbers. This forces your brain to slow down while doing the mundane task.Try to say each individual number slowly as well. 900-90-9, 900-90-8, 900-90-7, etc etc etc.
The reason to do this is because if you go from say, sitting on SARP talking with people and having fun despite the fact that you are physically tired, your brain is still active. Very active actually. Without doing anything to slow your mind down, it could easily take up to an hour, hour and a half for your brain to bring down the activity level. Counting also allows you to block intrusive thoughts, which is another cause of your brain being active. It goes from active to inactive, the jolt is so big that it could force you to think of something. Often negative aspects of your day or life, like embarrassing moments, times you got in trouble, or arguments that you have had in the past. The further back they are, the more likely you are to remember them at this time, but the general time is between 2-7 years from my experience, unless the moment is particularly "traumatizing" for lack of a better word..
On top of this, try not to move around. The human body is programmed to go to sleep after a certain amount of time of inactivity like a computer. Approximately 15 minutes of minimal thought, slow breathing, and no messages being sent to the body. At first it will be hard, but as you get used to it, you'll find you can go to sleep in a snap.