When A. Roger Ekirch went to the trouble to look he found a multitude of references to polyphasic sleep patterns in pre-industrial societies. That is a sleep schedule before the invention of the light bulb when sleepers wake for a couple hours after about four hours sleep then go back to sleep for another four hours. So people slept just like animals before we decided to ruin our sleep cycles with artificial light so we can hang out after dark.
—David Foss