Yes, it is a simple regimen: At least a half hour before bed, turn down all lights and light-emitting objects. This means no computers or television. Do not do anything in your bed other than sleeping or sex. If you want to read until bedtime, move yourself to a different location, like a comfortable couch. If you are having trouble sleeping at a given time, you may try melatonin. I don't have to follow all of these rules now that I've developed the habit, but I find my sleep is significantly improved when I do. Oh, and don't go to sleep drunk, either.

I had really bad sleep issues for years and what finally fixed it was not keeping my phone, laptop, or desktop anywhere near the bedroom. When I was younger I would fall asleep quite naturally no matter what I was doing or where. But now, even if I wasn't on them, having them near to hand would keep me up. They sort of sabotaged that in-between phase, just before you fall asleep.