A new study on the sleeping patterns of primates and other mammals, including humans, revealed that humans evolved to sleep more efficient.
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.
While humans make it through an entire day with an average of seven sleeping hours, other mammals such as macaques and mouse lemurs need 14 to 17 hours of sleep each day.
Even if we sleep shorter hours, scientists discovered that compared to other species, our sleep is more efficient, making us better rested. This is because humans spend more time in deeper stages of sleep, when other mammals spend more hours into lighter stages of sleep.
According to the scientists, humans spend about 25 percent of their sleeping time in a dream state named REM – rapid eye movement. In comparison, primates like African green monkeys, mouse lemurs and mongoose lemurs spend only up to five percent in REM state.
One of the members of Duke’s research team – David Samson – spent almost 2,000 hours observing the sleep of orangutans in REM and non-REM states as part of his dissertation. He argues that human’s ability of having a higher quality of sleep while sleeping shorter periods is unique.
Studies from a few years ago argued that people’s sleeping behavior in present represents our capacity of adapting to electric light, assuming that before electricity people were sleeping longer.
However, David Samson disagrees with the findings of those studies, claiming that artificial lamp cannot be the only factor which triggered the change. More than that, he points to another study which analyzed the sleeping behavior in hunter-gatherers societies from Tanzania, Bolivia and Namibia, living without electricity.
According to Samson, if electricity was the only factor that led to the changes in our sleeping habits, than people living today in regions without electricity should be sleeping longer than us. But the research on the hunter-gatherer societies revealed that they weren’t sleeping longer than humans living in electrified areas.
In conclusion, Samson and his research team claim that humans have replaced quantity with quality over the time. They believe that ever since humans climbed down of the trees and started sleeping together around the fire, humans evolved to sleep more efficient.
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