Don’t use your phone at night. If you absolutely have to, enable adaptive warm light (if there’s such a feature on your phone), which gradually turns the white balance to warm in the evening. This is because staring at the screen will send the signals to your brain to wake up, especially the blue-ish spectrum of light, plus whatever content you’re engaging with (news, social media, texts from friends) will make your mind occupied.
But again, best is to not use your phone at all.
Read a book. Pick a topic you’re interested in, buy a book and just read before you sleep. Yes, I see the contradiction - an interesting book will make your mind occupied too. Yet I find that a book relaxes me in my own world, while on your phone you’ll meet many different topics, lots of quick stimuli, maybe that’s why. I don’t know.
These strategies work for me.
Zuckerberg has mental illness.