The Wall Street Journal notes in a recent article about the rapper Jay-Z, newly hired as a record company exec, that he may have a hard time "synchronizing diurnal rhythms" with both his club-going late night crowd and his power-breakfast executive colleagues.
I remember when Saul was small that he wasn't ever really sure when night and day was and so he didn't sleep at night. You can hire a consultant (again says the WSJ) to help you sync your baby's diurnal rhythms, rates $150/hr and up - perhaps not too much to spend if you have too much money and not enough sleep.
My days tend to run a little bit longer than 24 hours, so it's easy to get up early on Mondays, and very hard to get up early on Fridays. On the weekends it's easier, less to keep track of then. I'm starting to chart sleep patterns in iCal (using a separate calendar layer) just to see if that's really true.