I usually sleep 9h from 3 to 12. But, when I was on a conference last year, where I had to get up early for events for a whole week, my rythm changed and I sle

I usually sleep 9h from 3 to 12. But, when I was on a conference last year, where I had to get up early for events for a whole week, my rythm changed and I slept from 12 to 9. This kept going on for two weeks or so, then I was back to my old schedule.