Despite fears of technology eating into our nap, we may be slumbering for longer than ever before and we may have misunderstood what sleep is for.

They say that an elephant never forgets. It is also often stated that one of the functions of sleep is to consolidate memories. If both of those things were true, then you’d expect elephants to sleep a lot – but the truth is, the massive pachyderms, which have the biggest brains of any land mammal, sleep just two hours each night.

Even though we sleep almost every night of our lives, it is also one of the most commonly misunderstood aspects of behaviour. It turns out that a lot of common ideas about sleep, much like the example above, are simply incorrect.

Have you heard, for example, that thanks to electric lighting and the faint glow emanating from the smartphone screens we stare at before going to bed, we get fewer hours of shut-eye than our hunter-gatherer ancestors?

“Many people have heard this so many times through the media that they believe it,” says Jerry Siegel, director of the University of California Los Angeles Center for Sleep Research. He admits it’s a compelling story, even though it is – probably – completely untrue. “The trouble is we don’t really have any data on this,” he says. “The devices that we use to measure sleep weren’t invented until long after the invention of electric light.”

Since it’s impossible to figure out how much time our ancestors spent sleeping, Siegel decided to do the next best thing. He travelled to Tanzania, Namibia, and Bolivia, spending time with contemporary hunter-gatherer groups. These people are born into an environment that is as close as can be found today to the one our ancestors would have lived in.

– Jason Goldman

Read more: The surprising truth about why we sleep and how much we need

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