Is it so surprising? The key takeaway could be rephrased “Healthy humans living under conditions similar to our evolutionary past naturally sleep an optimal amo

Is it so surprising? The key takeaway could be rephrased “Healthy humans living under conditions similar to our evolutionary past naturally sleep an optimal amount of time at night.” > When I get under 6 hours I see a clear drop off in performance. Or is it “When I temporarily find myself in an environment with stress-levels similar to those of the people in the study I a) start to perform like them on modern day tasks and b) start to sleep like them.”?