Humans Evolved To Get Less, But Better Quality, Sleep

According to the study, humans need shorter sleep because their sleep is more efficient than other primate.

Analyzing the scientific literature and databases containing information regarding sleeping patterns of hundreds of mammals and tens of primates, researchers at Duke University observed that humans sleep way fewer hours than even our closest relatives, like orangutans and chimpanzees. A new study suggests human sleep is more efficient than that of other mammals because we have evolved to sleep for fewer hours, in deeper sleep stages.

The researchers believe that this evolutionary shift towards shorter, more efficient sleep could be partly due to the transition of sleeping in “tree beds” to sleeping on the ground as we now do. Chimpanzees, our closest animal relative, generally sleep around 11.5 hours a night.

Shorter sleep also freed up time that could be devoted to other things, like learning new skills and forging social bonds, while deeper sleep helped to cement those skills, sharpen memory and boost brainpower, Samson said. Estimates have shown that primates tend to spend less than 5 percent in REM sleep. In fact, about 25 percent of our overall sleep is spent in rapid eye movement (REM) sleep-a deep stage of sleep.

The human sleep gap isn’t merely the result of round-the-clock access to artificial light from streetlamps and computer screens, the researchers say. Meanwhile, deeper sleep is necessary to consolidate these skills and leads to “enhanced cognitive abilities”.

“Humans are a unique species and given the intuitive concept that our sleep is linked to how we think, feel and behave, I was less surprised and more excited about the findings that support the idea that sleep has played a part in the evolution of our species”, Dr. David Samson, an evolutionary biologist at the university and a co-author of the study, told The Huffington Post.

However, as adults we long for the time when we had so much time to sleep and didn’t take advantage of it. We now have to get up early to go to work and with everything there is to do on a daily basis, we usually end up going to bed a lot later than we’ve planned. These, said the authors, are habits that could have made human ancestors get the most quality out of their sleep with the most time efficiency. It has been ascertained that people who use modern technology require more sleep than do hunter-gatherers. They said that early humans shortened their sleep patterns long before artificial light. Out of all the primates, humans distinguish themselves by getting the least amount of sleep.