Another personal anecdote to support this; I’ve done this sort of “reset” more than once, and there is a qualitative difference between getting 9 hours of sleep between 10pm-7am and 1am-10am for me. Your mileage may vary, but that 3 hour shift is the difference between feeling like a winner or feeling like a loser for me. I don’t know if it is psychosomatic, but I also don’t care if it is as long as it keeps me feeling good.
As a personal anecdote: I once slept for 10.5-11 hours a day for about 2 weeks. I decided that I need to catch up on sleep, so I went to bed at 8PM every night, fell asleep by 9 and awoke between 7:30 and 8. After about 2 weeks I stopped falling asleep by 9 and would fall asleep around 11 and wake up at 7, at which time I stopped my "sleep fattening". I did feel like a weirdo going to bed at 8, but it felt great at the end.
YMMV, but if you can sleep for 12 hours a night I would consider letting your body do it for at least several days to see if it would switch to a different mode that your would like more. My 2c.