Sleep guidelines from the National Heart, Lung, and Blood Institute recommend that adults get between seven to eight hours of sleep daily but findings of a new study involving present-day primitive societies suggest that most people may only need six to seven hours of sleep at night.

A growing number of studies blame artificial light, particularly those from smartphones and other modern-day devices, for people's inability to get sufficient amount of sleep at night.

It appears though that prehistoric people, who are known to recharge their body naturally by sleeping and waking according to the rhythm of the sun, are also "sleep-deprived."  

In a study published in the journal Current Biology on Oct. 15, Jerome Siegel from the University of California in Los Angeles and colleagues looked at the sleep patterns of three of the world's last remaining groups of hunter-gatherers who live in Africa and South America.  

Because these societies do not have access to electricity and other modern-day distractions, they are believed to have the same natural sleep patterns as the ancient humans who lived over 10,000 years ago.

During the three-year study period, the researchers found a striking uniformity in the sleep patterns of the subjects despite that they are geographically isolated. All three groups sleep a little less than six and a half hours at night on average and they do not take naps.

"The observed patterns are not unique to their particular environmental or cultural conditions but rather are central to the physiology of humans living in the tropical latitudes near the locations of the San and Hadza groups, where our species evolved," the researchers wrote in their study.

"Our findings indicate that sleep in industrial societies has not been reduced below a level that is normal for most of our species' evolutionary history."

Siegel and colleagues also found that sunset does not induce sleep in these people and that sunrise does not necessarily wake them up. Contrary to the common belief that primitive people sleep once it gets dark, the participants involved in the study were also found to stay up a a little less than three and a half hours after sunset on average.

"It's difficult to envision how we can claim that Western society is highly sleep-deprived if these groups that live without all these modern distractions and pressing schedules sleep less or about the same amount as the average Joe does here in North America," said University of Toronto sleep expert John Peever.