I usually go to bed around 2AM to 5AM, and wake up at 1PM to 3PM. Its an accident, I started going to bed later and later, about an hour longer a month. I can't do it any later.
Its easy to do this if you have a late night job, as did I. However I have to go to bed weirdly early if I want to do something the next day.
I'm clocking off at 2AM and waking up at 9AM today (its 12:40AM currently here) as I'm meeting a friend for lunch. Confuses my stomach, not sure how well I'll eat.
Not very healthy really. I've slept upside down for about a year, I plan to even it out again this year and go back to 1-2AM nights and 10AM mornings.