My 9 year old that has problems falling asleep most every night?

My 9 year old has issues falling asleep most every night. We have been trying different things to help him relax (music, relaxation, breathing, silence, bathes, warm milk, white noise, even went as far as trying regular noise, lol) but nothing has worked. When he was younger (4 and 5) the Dr told me to give him benedryl but that was a short term fix. I have tried everything I can think of, does anyone have ideas that help children get calm? He grows very frustrated very quickly tjhat he can't go to sleep which only prolongs the process of him falling asleep. Any tips would be appreciated. Thanks!