Study of sleep patterns of groups living in Tanzania, Namibia and Bolivia with lifestyles similar to our paleolithic ancestors shows similar late-night habits to humans with internet and TV-based routines. …
Unable to travel back in time to monitor the sleeping habits of our paleolithic ancestors, [Jerome Siegel, professor of psychiatry at the University of California in Los Angeles] worked with three groups of people who live life much as our forebears did for millennia. He asked members of the Hadza in Tanzania, the San in Namibia and the Tsimane in Bolivia to wear watches that recorded their sleep. In total 94 people in total were tracked for six to 28 days each throughout the seasons, creating sleep data for 1,165 separate days.
He found that none of the groups went to sleep at sundown, and instead stayed up for an average of three hours and 20 minutes longer. “They are up for a good two hours after it is as dark is it ever gets,” Siegel said.
Nor did the people sleep that long. A typical night’s rest amounted to six hours and 25 minutes, at the low end of sleep times recorded for people in Europe and the US. They slept an hour longer in the winter than in the summer.