Wow! This is an interesting topic to research. Personally, my ideal sleep schedule is around 6–8 hours, like you, but I can’t always achieve it. I don’t think ancient people had the same sleeping habits as we do today. They had to keep the fire going, go hunting early in the morning, or adapt to other survival needs.

I also heard that the concept of three meals a day was created during the industrial era. In the past, having fewer meals was likely more common, I think. Interestingly, my DNA test shows that 8 hours of sleep is the most comfortable schedule for me.