Most of us sleep between six to nine hours a night, meaning we spend about a third of our lives asleep. This may seem like a long time, but we actually sleep the least among all the primates.
According to an article by Robin A. Smith at the World Economic Forum, the secret is that our sleep is more efficient. Researchers from Duke University found that humans are exceptionally short sleepers — getting by on an average of seven hours of sleep a night, whereas other primate species, such as southern pig-tailed macaques and gray mouse lemurs, need as many as 14 to 17 hours.
What’s more, our sleep tends to be more efficient, meaning we spend a smaller proportion of time in light stages of sleep, and more of our sleep time in deeper stages of sleep.
The researchers attribute the shift towards shorter, more efficient sleep in part to the transition from sleeping in “beds” in the trees, as our early human ancestors probably did, to sleeping on the ground as we do today.
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, the study said.
As BBC pointed out, the third of our lives we spend doing so is certainly not wasted. Our big brains took millions of years of evolution to get there, so it's only fair that we reward ourselves with a lifetime of adequate rest.
Helgi Library 
