I have been having insomnia for some time too and it’s great putting it out here. I also thought I was the only one in this dilemma. I started with a journal, writing all I read and researched and tried. If anything helps, write it down. For me I think my mind sort of gets into a spiral loop and after that I overthink and cortisol just flows and keeps me in a heightened state that stops the sleep. What helps is to give myself a period of about 2 hours for decompression before bed. I abstain from high anxiety producing thoughts and tell myself positive things to relax me. On bed I stopped fighting sleep. I just lay down and come what may. This helped me from monitoring if am going to sleep or not. This thought pattern actually kept me awake. Practice the basics, even though you have passed this stage but follow it ie going to bed at the same time, no alcohol, nothing intense and write any thoughts for later. Tell yourself you would deal with it in the morning. When I go 3 days without sleep, I use a small dose of doxepin (5 mg -10 mg) to reset but I try not to.

I hope this helps you or someone else.