It's interesting to compare this with non-solar based pattern as in the Siffre cave experiment where they ended up falling into 48 hour sleep cycles instead.

I also fall into the camp where I believe that there are probably a variety of different sleep cycles that people are just predisposed to. I haven't seen any studies definitively indicating that there are a common sleep cycle. Even anecdotally, I know several people that are just more alert at night.

I've always wondered if there was a way to structure society so that there could be more time variety in socially needed functions. Perhaps one bank could be open 9-5 but another bank could be open 5-12. Or at the very least, improved flexibility for jobs where constant communication is not needed and can be done asynchronously. A set of core hours where communications could happen and then allow workers to work on their own cycles, taking naps as needed so that they can operate when they are most productive.