He sounds a little like me... I have NEVER been able to quickly fall asleep. Even as a child, it took me 2-3 hours to get to sleep. Heck, even now, when I use all sorts of non-medication sleep aids, I still take over an hour.
My brain just doesn't shut off.
Counting sheep and meditation don't work well for me. I have to concentrate too hard on it, which keeps me awake. My best bet to fall asleep is to start a "guided dream" where I pretty much fantasize about anything I want... When I was a kid, it used to be things like getting a horse, or living in a tree house... things like that. I would lay in bed, in the dark with my eyes closed while I directed what I wanted to happen in my fantasy. Eventually, my fantasy would start taking on it's own aspects without my direction, and I would just drift off into sleep.
I had a sleep study done when I was young, and that is what the doctor suggested before trying me on medication. It worked well for me! (I did try medication for a while when I was in high school, but I don't react well to a lot of medications... so I went back to my dreaming. lol.)
ETA after reading some of the other answers, I wanted to add...
When I was young, we always had a 1hr calm-down period, where we stayed in bed and read with the lights on. (Bedtime at 8:00, lights out at 9:00) Up until I was about 17, I NEEDED some kind of noise, be it TV, radio, or outside noise (like a storm or something...) to fall asleep. After that, to this day I need it to be mostly quiet. I can NOT sleep at ALL if the TV is on, and I have a hard time with the radio. Lol. I would experiment a bit to see what works better for your son in that regard.