Yes, but still... I agree that it seems likely that in preindustrial times, most people just went to bed at dark and got up at light. Depending on the season that might be 12 hours or more, so they possibly didn't actally sleep all that time, but they were probably just quietly in their homes/shelters even if they were awake.

Yes, biphasic sleep.

https://en.wikipedia.org/wiki/Polyphasic_sleep