For me the difficulty was switching my brain off. I tried breathing exercises, and meditation, but I couldn’t get them to work (maybe I was doing them wrong)

The thing that worked for me in the end was a static mental imagery, I was listening to a YouTube video and it said to imagine yourself on a lake, in a boat, looking at the sky, with no thoughts - this particular image didn’t work for me, but then they suggested imagine yourself in a dark room in a hammock - this image worked for me, and I was able to silence my mind and sleep quickly

After about 20 days of doing this, some kind of Pavlovian conditioning happened where my body understands that bed + this image means sleep now