I have met a fair number of early risers who simply go to bed early.
I've long assumed it's probably due to people who'd do bad things with any sort of useful, "I'd like to go to sleep in the next 15 min, oh and no side effects if the fire alarm goes off in 30 min" kinds of drugs that they aren't a common OTC item.
I had to do it for several years.
I felt like absolute shit every morning. I felt sick and couldn't eat before 10.
Every Day.
I don't have that now I can get up later.