The normal sleep pattern of our ancestors was to go to bed shortly after the sun went down, then wake when the sun rose.
Best Answerhttp://newsroom.ucla.edu/releases/our-ancestors-probably-didnt-get-8-hours-a-night-either
http://www.bbc.com/news/magazine-16964783 These are a couple of articles -but for some reason, I can't seem to locate the original source of the data.
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