If you're reading a book to learn something, you need to be focused. So one thing i do is not read directly before bed. I don't read when i'm in a hyper distracted state. And if that's the case, it's not worth reading that book. If you do want to read before bed or to relax, pick up a work of fiction. Or you can do non fiction books, like meditations by marcus aurelius. They're just sort of stories you can get lost in and turn the mind off.