Unlike our ancestors who lived in technologically advanced times, there is much written about how modern lifestyles mean that we no longer get enough sleep. However, an analysis of 54 sleep studies conducted around the world has shown that people in small, non-industrial societies actually sleep less than people in industrialized communities.

“Everyone I talk about in Canada and the US are talking about how bad their sleep is.” Leela Mackinnon At Toronto Mississauga University, Canada. “The numbers don't show that.”

It is often assumed that the rise of gadgets like big screen televisions and smartphones means that people today are less sleepy than in the recent past.

However, many studies reporting sleep declines over the past few decades are based on asking people how long they spend sleep. This is an unreliable measure. Even using this method, The results are mixedmany studies have found that there is no change or even an increase in sleep duration.

Studies based on more reliable measurements, such as using physical activity monitors and electrodes to monitor brain waves, have not declined over the last few decades. For example, we found a 2016 review of 168 studies. There is no decline Sleep period for the past 50 years.

However, these studies have been conducted in developed countries and reveal the question of whether people had more sleep before industrialisation. Wrist-based activity monitors are now available, making it easier to study sleep in a non-industrial society.

Such studies have revealed an incredible short period of sleep. For example, among hunter-gatherers, Sun sleeps on average 6.7 hours per night, Hatza sleeps 6.2 hours, and Bayaka sleeps 5.9 hours per night. The shortest time ever found is 5.5 hours of sleep in the HIMBA community in Namibia, a herdsman of nomadic livestock.

McKinnon and her colleagues David SamsonUniversity of Toronto, University of Mississauga, is also involved in several such research. They now compare sleep habits in industrialized societies, including the US, Australia and Sri Lanka, with people from small, non-industrial communities, including the Amazon, Madagascar and the Pacific indigenous people.

Overall, the analysis is based on 54 studies that include direct measures of sleep in people over 18 years of age without serious health conditions. In total, only 866 people are involved in these studies, but the dataset is the most comprehensive to date, says Samson. “It's the best now.”

Overall, these individuals slept on average 6.8 hours, while in non-industrial societies the average was 6.4 hours, while in industrial societies it was 7.1 hours.

The two also found that people from the industrial world were asleep for 74% of their time in bed.

McKinnon and Samson also evaluated the regularity of people's circadian rhythms using a measure called the circadian function index, where the score of 1 is perfect. In non-industrialized communities, the average was 0.7 compared to 0.63 in industrial societies.

Samson attributes the higher period of sleep and increased sleep efficiency in industrialized societies to conditions that encourage sleep more. “We see that we have some real benefits from the safety and security of our sleep scene,” he says. “There's no need to dodge the night or predators with rival human groups.”

Conversely, people in industrial areas are less exposed to clues that help to maintain a circadian rhythm, such as low night temperatures and bright daylight exposure. Although they did not appreciate this, both MacKinnon and Samson said that a low normal circadian rhythm would have a negative effect explaining why many people perceive their sleep as poor. I doubt there is a possibility of giving it.

What is not clear from the paper says that individuals in these 54 studies are representatives of the overall population. Nathaniel Marshall At Macquarie University in Sydney, Australia. “Special sampling is required to make a statement about epidemiological prevalence,” he says.

Samson said he looked into whether large sample sizes could change results, and concluded that there was no significant difference.