Another insomniac here! Mine started when I was eight so many years ago.. I have it on/off, go through stages of it. My worst has been a year of 1-2 hours sleep a night, I was hallucinating and paranoid, just dreadful. GP's never much help- it's anxiety they tell me, try more exercise, cut out caffeine etc.
Tried everything except pills which I point blank refuse to get hooked on. Someone told me to eat a banana and almonds before bed to help hormone levels balance out, it worked for a few days then stopped. I've tried no caffeine, sticking to a set routine of when I get up and go to bed, camomile tea, special sleep teas, yoga, meditation, vigorous exercise, sorted the feng shui in my room, reading, warm lavender bath, no TV or food after a certain time... just ARGH!
My issue is I overthink. I'll lay in bed worrying about what someone said to me two weeks ago for example. And my worst thing is when there's a social event coming up, i'll worry about it and not sleep for weeks because I HATE social events 
. I used to do the same every sunday before school, just lay there worrying! I'm not sure if you CAN stop worrying tbh. I've come to accept i'll always be an insomniac anyway, it's been with me for so long I doubt there's any real 'cure'.