I have also done a similar thing - I think some call it "free running" sleep schedule. Since I work from home, and since I moved to a new city and didn't have any friends or anything, I just worked until I was too sleepy and then slept until I was awake. I ended up shifting about 2 hours forwards every day, so in 2 weeks I had gone all the way around the clock back to normal day/night schedule. It was kinda fun.
