I have to admit to being an insomniac also.
It's a pain, as a lack of sleep leaves you feeling, as you know, like shite.
The only thing that ever worked for me was sleep deprivation. Yup madness, but it can work.
Basically to do it, you set yourself out on a months (or two) sleep deprivation. Basically training yourself only to sleep at night.
No napping or snoozing during the day, no matter who shite you feel, stay awake and find things to do keep you awake no matter how focced you are. Remember it's only for a month or two.
Then combine that with limiting the time you allow yourself to sleep at night. 6hrs should do. That's 6hrs in bed, if you don't get a 6hrs sleep, tough, just keep following the routine.
Stick to it for one hellish month (or two). In fact towards the end of the month it should get easier, and if you are an insomniac, despite being somewhat sleep depraved you should feel better, as hopefully, the 4 and a half to 6 hours sleep your are (hopefully) getting each night is quality deep sleep.
A word of warning however. It can be addictive.
I guess also there must be different types of insomnia. I'm the can't get off to sleep type, combined with being a fussy sleeper.
A couple of drams at the end of the day also helps me, though any more than that impacts on quality of sleep.
Oh to be a sound sleeper. It must be wonderful.