Over the years I’ve had to adapt to different environments.
In College I functioned quite happily on a few hours of sleep daily. Between classes, making art, working at the jewelry store, and women, there wasn’t much time for sleep, so 2 to 3 hours a night was standard.
When I was a freelance matte painter my sleep schedule adjusted to what felt natural, about 4 AM to 10 AM. I could get more done between midnight and 4 AM than any other time of the day.
Nowadays this production requires another adjustment, so I’m in bed before midnight and up around 7. I never use an alarm. Never needed one. Usually wake up rested, despite the best efforts of my CPAP machine to deny and destroy my sleep. What a racket.
When I retire I’ll see where my schedule settles.