Of course I’m making a few assumptions here, but it sounds like your problem is that you just don’t shut off that part of your brain to allow it to relax, so you can fall asleep. I don’t care how dark or redshifted your screen is, it’s also the content on it and what it is making your mind do.

Try stopping all electronics mid evening, watch the sun set, and read or write (not on electronics!) for an hour or so.