Humans Sleep Less Than Primates--But We Do That Efficiently?

If sloths, pandas and housecats -- and many primates -- have humans beat for hours spent sleeping each day, we may be sleeping more efficiently than our closest animal relatives, says a new study.

That is, researchers from Duke University say that humans get by on an average of seven hours a night, but other primates -- including gray mouse lemurs and southern pig-tailed macaques -- may need 14 to 17 hours, according to a release.

As it turns out, humans spend a smaller part of our sleep time in the light stages, and more time in the deeper stages. Our rapid eye movement sleep, or REM (a dream state) takes up about 25 percent of our sleep. In contrast, mouse lemurs, African green monkeys and mongoose lemurs have a REM portion over slightly over five percent, confirmed the release.

Not very dreamy, some of those other primates. "Humans are unique in having shorter, higher quality sleep," study co-author David Samson of Duke said in a statement.

Also, it's important to add that we're not (necessarily) all hopped up on the lights of electronic devices left on in our bedrooms. A separate study among hunter-gatherers in Tanzania, Namibia and Bolivia learned that those groups had slightly less sleep than those of us living in electrified society.

The study has some theories regarding why humans sleep with more quality than quantity: Maybe first, humans transitioned from sleeping in trees to sleeping on the ground. Then we began nodding off near comforting fire and in groups, where we felt safer from predators and could keep warmer.

Consequently, humans also were able to use their extra time learning new skills, sharpening memory, raising brainpower and deepening social bonds, notes the release.

The findings were recently published in the journal Evolutionary Anthropology. 

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