Megan McArdle’s circadian cycle is set in its ways.
I have the opposite problem. After a quarter-century of more night shifts than days, and a decade of constantly rotating shifts, my body has no set pattern. I can still go days without sleep, or conversely hibernate for fourteen hours. That latter is problematic. I need an extra alarm clock for insurance.
My appetite is similiar. After having done one extended fast, and numerous shorter ones, at a moment’s notice I could fast for a day with no real problem. (Anything longer and the caffeine withdrawal is murderous. You have to taper down prior to an extended fast.) Unlike my sleep “cycle”, I’m grateful for the food one.
How about you guys? Any bio-oddities?
World's Only Rational Man 
Nope. It’s amazing how procreating puts you on a very solid schedule. My hubs, on the other hand, suffered the fate of rotating shifts for about a year and a half. One week 5am to 1pm, 2nd week 1pm to 9pm, 3rd week 9pm to 5am, then repeat.
During that time, he was utterly useless. A shell of his real self.
Does your sked shift as often? If yes, eek. Sorry.
I’m actually 8 to 4 right now…because doing the rotating day/night thing for 4 years almost broke me. Will probably go back on it in a few months, but won’t stay on it nearly as long next time.