I had so much trouble with insomnia a few years back - I remember not being able to get sleep for at least 3-5 days straight on multiple different occasions. I thought I was going to die at least two of those times it happened.
These days my ability to fall asleep feels like a superpower (because - 1. I know just how absurdly many people out there are functioning on less than optimal sleep on a daily basis, and 2. I know I'm not the only one who has had trouble with falling asleep).
These are the bits of advice I have:
1. I've woken or havent been able to fall asleep because I was hungry. Always try to have eaten at least one satiating meal a day. Also make sure you're not dehydrated or have to pee.
2. Don't ever worry or intentionally think that you have to fall asleep. The stress, the cortisol, and the excitement(when you start falling asleep) will keep you awake. Going one night without sleep is not the end of the world. At worst you were really really relaxed in a nice cozy bed for 8 hours, so take comfort in that time.
3. This one is the most important: think about your brain like its some sort of muscle. If it's engaged its sort of 'flexing', and its very hard to fall asleep if its flexing. If I just 'unflex' my mind the way I would let go of my grip, the next thing I usually notice is that its morning and my alarm clock is waking me up.
Other than these things, everything else I've seen had little affect on my abilities to sleep when I had insomnia - working out until exhaustion out didn't work, neither did weed, neither did alcohol, and neither did induced food coma, reading a book, watching tv, counting sheep. And when I learned again how to fall asleep, I haven't had a problem with blue light, I haven't had a problem with caffeine, I didn't even have a problem with a lot of noise. These things help or hurt your ability to sleep but it doesn't ultimately determine whether or not you do.