![]() But that was accompanied by a hefty drop in non-REM sleep, they note. People now spend an average of 1.56 hours of snooze time in REM, Nunn and Samson estimate. The 36 percent shortfall between predicted and actual sleep is far greater than for any other species in this study. In fact, they sleep only around 7 hours daily. And species that travel in small groups or that inhabit open habitats along with predators tend to sleep less.īased on such traits, the researchers predicted humans should sleep an average of 9.55 hours each day. For instance, nocturnal animals tend to sleep longer than do those awake during the day. For this, they looked at earlier studies of links between sleep patterns and various aspects of the species’ biology, behavior and environments. The researchers then predicted sleep values for each primate. Those studies largely involved captive animals that had worn electrodes that measured brain activity as they snoozed. Such estimates relied on previous measurements of primate sleep. ![]() For 20 of those species, enough data existed to estimate how long the REM and non-REM portions of their sleep would last. Nunn and Samson considered various traits about the animals and their environments in calculating how long they would expect each species to sleep. Some other primates sleep in several bouts that vary in how long they last. ![]() People get most sleep in just one bout per day. If the findings hold up, though, Capellini suspects that a change in sleeping patterns also may have lessened humans’ sleep time. Samson/American Journal of Physical Anthropology 2018 They were one of three primate species (dark blue bars) whose snooze times differed greatly from what researchers had predicted. Humans stand out as averaging the fewest hours daily. This chart shows a subset of data on how long primates sleep. There may be 300 or more primate species. However, she cautions, their sample of 30 species is too small to reach any firm conclusions. She says the new study does show that people may sleep for a surprisingly short time for primates. Isabella Capellini is an evolutionary biologist at the University of Hull in England. “But something had to give as we slept less.” “It’s pretty surprising that non-REM sleep time is so low in humans,” Nunn says. And it has been linked to learning and memory. That has left less time for sleep.Īs sleep declined, rapid-eye movement - or REM - sleep took on an outsize role in humans, Nunn and Samson propose. The second may reflect the intense pressure humans face to learn and teach new skills and to make social connections. At that point, people probably had to spend more time awake to guard against predators. The first stems from when humans’ ancestors descended from the trees to sleep on the ground. The researchers argue that two long-standing features of human life may play into our short sleep times. Nunn and Samson shared their findings online February 14 in the American Journal of Physical Anthropology. Most other primates in the study typically sleep as much as the scientists predicted they should. Humans averaged just seven hours of shut-eye.īased on lifestyle and biological factors, however, people should get 9.55 hours, Nunn and Samson calculate. Most species slept between nine and 15 hours daily. In their new study, the two compared sleep patterns in 30 different species of primates, including humans. Samson works at the University of Toronto Mississauga in Canada. Nunn works at Duke University in Durham, N.C. They study how humans have evolved to behave the way we do. People have evolved to sleep much less than chimps, baboons or any other primate studied so far, a new study finds.Ĭharles Nunn and David Samson are evolutionary anthropologists. ![]() If it seems like you’re not getting enough sleep, you’re not alone.
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