Guilty of not getting the recommended eight hours of sleep last night? Don’t worry, you’re not alone. According to a 2013 Gallup survey, 40 percent of Americans fail to meet this standard. However, a recent study suggests eight hours of sleep may not be as integral to our health as we have been led to believe.

In the first-ever study on the sleep habits of modern people who maintain a traditional hunter-gathering lifestyle, a team of UCLA researchers discovered both how sleep patterns have changed and remained the same since the onset of industrialization. In order to better understand the sleep patterns of the past, the team studied the sleeping habits of three present hunter-gatherer tribes: the Hadza of Tanzania, the San of Namibia, and the Tsimane of Bolivia.

Two years ago, Dr. Jerome Siegel, the leader of the research team and a UCLA professor, first began asking anthropologists around the world to measure the sleeping and waking times, as well as the light exposure of the traditional people they were living among. With the help of contacts at Hunter College, Yale University, UC Santa Barbara, and the University of New Mexico, Siegel was able to accurately measure how long traditional adults slept during summer and winter seasons. Siegel was also able to document their body temperatures, the temperature of their environment, and the amount of light they were exposed to. By the end of his research, Siegel and his team were able to measure the sleep records of 94 adults for a total of 1,165 days.

Results gave intriguing insight into human sleeping patterns in an environment completely void of technology, and showed that despite lack of artificial lights, people still stayed awake an average of three hours and 20 minutes after sunset.

"The fact that we all stay up hours after sunset is absolutely normal and does not appear to be a new development, although electric lights may have further extended this natural waking period," Siegel said in a statement.

In addition to staying up after sunset, the amount of time that traditional people spent asleep also strayed from common belief.

"There's this expectation that we should all be sleeping eight or nine hours a night, and that if you took away modern technology people would be sleeping more," said Gandhi Yetish, a Ph.D. candidate at the University of New Mexico, who spent 10 months with the Tsimane. "But now for the first time we're showing that's not true."

While many recent studies have linked shorter sleep patterns with poor health, the researchers did not find this to be the case among the traditional people. Instead, the traditional tribes appeared to have significantly better health than people in more industrialized societies, despite getting less than the recommended rest. Even more interesting, insomnia, or being unable to fall asleep, was so rare among the traditional tribes that they did not even have a word for the disorder. Although it's difficult to trace one specific cause to insomnia, a condition that affects around 20 percent of Americans, Siegel suggested that changes in sleep temperature may play a role. The researchers observed that the traditional people consistently fell asleep and awoke at points of either temperature drops or increases — a behavior that no longer exists among those in industrialized cultures.

"In most modern environments, people are sleeping in a fixed temperature, even if it is reduced from daytime levels," Siegel said. "It may well be that falling environmental temperature is integral to sleep control in humans."

Source: Siegel J, Yetish G, Gurven, et al. Natural Sleep and Its Seasonal Variations in Three Pre-industrial Societies. Current Biology. 2015.