Snoozefest

Deep in a forest in Africa, a chimpanzee gets ready for bed. Every night, it climbs 15 meters (50 feet) up a tree. It collects branches and twigs to weave into a platform. Then it plucks leaves to make a comfy pillow. When the bed is complete, the chimp climbs in and dozes off.

A chimpanzee gets ready for bed. It lives deep in a forest in Africa. The chimp climbs 15 meters (50 feet) up a tree. It collects branches and twigs. The animal weaves them into a mattress. Then it plucks leaves to make a comfy pillow. The bed is finished! The chimp climbs in and dozes off.

David Samson is a biologist at Duke University in North Carolina. He studies how primates like chimps sleep. He watches them build beds in forests and snooze at zoos. Then he compares them with their closest relatives: us.

About a year ago, Samson noticed something. People sleep less than other primates, but we sleep more deeply. Samson suspects that’s because deep sleep improves human cognition, or thinking. It may have even helped us develop our powerful brains.

Samson noticed something about a year ago. People sleep less than other primates. But we sleep more deeply. Samson thinks he knows why. Deep sleep boosts human cognition, or thinking. It may have even helped us develop our powerful brains.

David Samson is a biologist. He works at Duke University in North Carolina. He studies how primates like chimps sleep. He watches them build beds in forests. He also watches them snooze at zoos. Then he compares the animals with humans, because we’re related to apes.

Scientists know sleep is important because people spend so much time doing it. By the time you turn 10, you’ve already spent about 2.6 years of your life fast asleep! 

If you’ve ever stayed up too late, you probably know why sleep matters. Without a good night’s rest, it can be hard to focus on schoolwork or conversations with friends.  

Scientists know sleep is important. That’s because people spend so much time doing it. By age 10 you’ve already slept about 2.6 years!

You probably know why sleep matters if you’ve ever stayed up too late. It can be hard to focus on school or talk to friends without a good night’s rest.  

While you’re asleep, your body prepares for the next day (see Sleep Cycle). Your heart rests and tired muscles repair themselves. During deep sleep, your brain stores memories and processes emotions. “If you go to sleep feeling upset, a lot of the time you’ll feel better when you wake up,” says Samson.

Dreams happen during a special type of deep sleep called rapid eye movement (REM) sleep. Your eyes move under your eyelids as scenery changes in your dreams.

Your body gets ready for the next day while you’re asleep (see Sleep Cycle). Your heart rests. Tired muscles repair themselves too. Your brain stores memories during deep sleep. That’s also when it processes emotions. “If you go to sleep feeling upset, a lot of the time you’ll feel better when you wake up,” says Samson.

Dreams happen during a special type of deep sleep. It’s called rapid eye movement (REM) sleep. Your eyes move under your eyelids as images change in your dreams. 

A few years ago, Samson began to wonder how different sleep habits affect the brain. So he turned to apes, humans’ closest living relatives. 

Samson visited an orangutan named Azy at the Indianapolis Zoo in Indiana. Azy usually makes his bed out of hay. But to help Azy sleep more deeply, Samson gave him pillows, blankets, and a mattress. 

Samson recorded Azy as the ape made his bed and slept. When the video showed Azy’s eyes moving, Samson knew that Azy was dreaming in deep REM sleep. “The nights when he had the super-bed, he had a deeper sleep,” says Samson.

Samson began to wonder how sleep habits affect primates’ brains a few years ago. So he visited an orangutan named Azy. He lives at the Indianapolis Zoo in Indiana. Azy usually makes his bed out of hay. But Samson gave Azy pillows, blankets, and a mattress. They would help the ape sleep more deeply. 

Samson recorded Azy as the ape made his bed and slept. The scientist watched the video. He noted when Azy’s eyes started moving. Samson knew that’s when Azy was dreaming in deep REM sleep. “The nights when he had the super-bed, he had a deeper sleep,” says Samson.

The next morning, Samson played memory games with Azy. Whenever Azy had slept more deeply, he performed better at the games. The deep sleep seemed to improve his cognition. 

That made sense to Samson. He knew that deep sleep helps humans think too. After a good night’s rest, for instance, people are better at remembering what they did the day before. 

Samson played memory games with Azy the next morning. Azy did better at the games if he had slept more deeply. The deep sleep seemed to help his cognition. 

That made sense to Samson. He knew that deep sleep also helps humans think. Here’s one example: People better recall what they did the day before after a good night’s rest. 

Not all animals sleep like we do. Giraffes, for instance, only take quick naps. So why not sleep deeply if there are so many benefits? Because it’s risky, Samson explains. 

Animals in deep slumber are less likely to wake up if a predator is nearby. That’s why many animals, such as dogs and cats, tend to sleep lightly. Even quiet noises wake them so they can quickly jump up and react.

Samson thinks humans are different thanks to our ancestors. Millions of years ago, early humans started sleeping in big groups. People could take turns looking out for predators such as saber-toothed cats. With less threat of attack, people could drift off into deeper sleep.

Not all animals sleep like we do. Giraffes take only quick naps, for instance. So why not sleep deeply if there are so many benefits? Because it’s risky, says Samson. 

Animals in deep slumber are less likely to wake up. That’s bad news if a predator is nearby. Many animals, such as dogs and cats, tend to sleep lightly. Even quiet noises wake them up. That way they can quickly jump up and react.

Samson thinks humans are different. We can thank our ancestors for that. Early humans started sleeping in big groups millions of years ago. People could take turns watching for predators, such as saber-toothed cats. That meant there was less threat of attack. The rest of the group could drift off into deeper sleep.

Around the same time, early humans began to think differently from other primates. They learned to build fires, make tools, and talk. Samson thinks this timing is no coincidence. Just like Azy, humans may have become smarter as they started sleeping more deeply. 

Samson hopes to keep studying how sleep helped our brains develop. “In a lot of ways, sleep is still a mystery,” he says. “But we’re starting to figure out how it makes people so unique.

Early humans began to think differently from other primates around the same time. They learned to build fires, make tools, and talk. Samson thinks this timing was no coincidence. Just like Azy, humans may have become smarter as they started sleeping more deeply. 

Samson hopes to keep studying how sleep helped our brains develop. “In a lot of ways, sleep is still a mystery,” he says. “But we’re starting to figure out how it makes people so unique.”