What some people don't get is that some of us are totally reversed from the "normal" sleep pattern. I feel my best, and always have felt my best, going back to the beginning, by sleeping from 5AM to about noon. I drove my mother crazy when at a few months age, I stopped going to sleep when they put me to bed and would stay up and cry, and the later, call for her all night. She tried keeping me up later and later, but it didn't do any good. She couldn't sleep while I was awake, so she was totally sleep deprived until I was about 2 and my dad convinced her that I would call her when I needed something. My mother turned that on him, and told me to call HIM. And I did, but not all that much.
This altered sleep pattern has afftected me my entire life. School, at least until college, was a nightmare. I was sick all the time, and felt bad due to forcing myself to try to sleep at night. I found out I could sleep at school much easier than I could at Midnight, if the teacher let me, and some did. One asked me what I did all night, and I told her, "I sit and listen to the radio talk shows with an earphone in a pitch black room and fall asleep around 4 or 5 am, then I had to get up at 745 for school", that's why I was a mess.
After high school was finally over, I stayed up all night and went to bed at 5, and felt better than I had my entire life! I went to school at night and it was great. No fighting sleep like I always had to do before and I FELT GOOD, and didn't get sick all the time.
Later on, I tried several times to work day shift, with bad results, so at the age of 25 or so, I decided that I would never work a "day" job again. A few years ago, my boss took a vacation and I had to work 16 days straight from 8AM till 430PM. I was such a mess at the end, I barely could drive home the last few days of it, I was so messed up, sleep wise. That's it, other than an emergency situation, no more day shifts for me. It's death.
My sister is a 12 hour person, she goes to bed at about 8 or so, and gets up 11 to 12 hours later. If she doesn't get all that sleep, she's as bad as I am working days.