That's not true, people used to wake up for several hours a night. There were also those up through the night tending fire and looking for predators. And darkne

That's not true, people used to wake up for several hours a night. There were also those up through the night tending fire and looking for predators. And darkness does not rule out sleeping during the day. https://www.sciencealert.com/humans-used-to-sleep-in-two-shifts-maybe-we-should-again https://www.sciencealert.com/humans-used-to-sleep-in-two-shi...