I suffered a bout of insomnia a few years ago. It was madness. So I empathize immensely.
My neurologist suggested I review m "sleep hygiene".
Meaning the overall environment where I'm sleeping. This is what we did and it worked for me after about a week.
I drink a glass of lukewarm water before bed.
We removed the tv.
Sleep and sex only in the bedroom.
No reading or eating etc.
My sheets are 800 TC Egyptian cotton, No blends.
I wash my sheets without any fragrance what so ever once per week no exceptions.
We keep a fan running for white noise.
The sleeping temp is about 65 year round. And I cool my room well prior to sleep.
I don't eat anything 3-4 hours before bedtime.
Limit alcohol especially within the few hours of bedtime.
All cotton lightweight t-shirt or tank for sleeping.
I have a good size aloe vera plant on bedside table, is good for air quality.
I also use Aveda Stress Relief composition oil roller every single night on my wrists, across my chest and a tiny dab under my nose.
It took a week or so, but I follow this to a T, even when traveling, and so far it's been working for me for the last 3 years.
I tried melatonin. But it was useless. And I refused prescription meds due to the side effects and half life.
Good luck. I know it's a maddening situation to be in. I empathize completely.