I know as a Christian I should not be jealous, but that post makes me jealous. LOL. No, I worked a midnight shift for 36+ years as a mechanic and electronics technician. (networking in later years). I would come home about 8 when I did not get stuck on OT, do some chores and go to bed about 11 or 12. By 3 pm, I was wide awake. I did some more things around the house and cooked supper for us because my wife got off late. At 8 pm, I would go back to bed and get up about 10:30 to get to work on time. I never learned to sleep all at once during the day.
I am not as active as you (maybe that is part of the problem), but I do work part time at an adult day care, and do my church work. I stay fairly active with chores like push mowing our one acre yard. Also, about four months after I retired four years ago, I had a six way heart bypass, which is going fine. The thing is, by 8 or 9, I go to bed. My wife stays up till 11. At 2 am, I am wide awake, so I do various things like post here. Then about 4:30, I will go back to be for a couple of hours. I salute you for making the smooth transition. It does not bother me that much, but it is not the norm.
Thanks for your response.