[ozlikethewizard]

Prior to the industrial revolution polyphasic sleep was pretty standard:

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

[dbacar]

That article does not say whether polyphasic sleep was standard because parents were synchronizing with their babies.

[Ferret7446]

The polyphasic sleep schedule was aligned with darkness, not random times throughout the day. Daylight was far too valuable for that.

[ozlikethewizard]

This varies, you still see some polyphasic sleep in countries that have very hot middle of the days, Greece + Spain off the top of my head. An intentional waste of daylight because the cooler mornings and evenings are better, but industrialisation has still reduced the frequency of these practices.