We have 24 hour schedules because the earth rotates about once every 24 hours. But what if humans were on a planet that didn't have 24 hour days? Would their bodies adapt to stay awake for far longer or shorter periods of time, then likely also sleeping longer or shorter, or would their bodies still gravitate towards a 24 hour cycle?
I assume people living near the poles would likely have the best idea of this, or perhaps those who have lived for an extended time in a space station. I would think that, though our bodies often adapt to their surroundings, that a roughly 24 hour cycle is healthiest for the body. This is because the body seems to do well when it gets enough sleep, but also shouldn't sleep too much, as one needs to eat and (optimally) work to stay in good health. Sleeping is often recommended to be 8 - 10 hours, but is that because of our 24 hour schedule?
So, if a human lived in an environment where daylight was too long/short to go by, or no star was available to go by, what would be the optimal time schedule for them? Would they still be inclined to go by a 24 hour time, even if they may not be familiar with such a schedule prior.
This is primarily to determine: if people lived on planets where the daylight schedule couldn't be used as days, or lived in space with no star to go by, what time schedule would they gravitate towards (likely for health reasons)?