Practice meditation. Drink an efficient amount of water. Darken your sleep area as much as possible. When I was younger I used to think in my head, “I’m laying in a dark, dark room” over and over. Now it’s the ocean crashing with each breath I take. I take myself outside of MY thoughts and worries, and nearly force myself into thinking about the waves crashing against the beach, or anything that may help calm you, like the wind blowing through the leaves.
If you can’t sleep, than it could be the fact that you haven’t disconnected. Take some time before bed, maybe half an hour or so, to just read, draw, write, meditate, shower or do anything not screen-related. This is the best way to prepare yourself for sleep. The rest will come.