How long elephants sleep

In fact, he notes, studies have found plenty of evidence that they can have long memories. Until now, horses were the record-holders for needing the least sleep. They can get by with just 2 hours, 53 minutes of sleep, Manger says. And other work finds that great frigate birds and pectoral sandpipers can perform well on less than two hours of sleep a day.

But the data do fit a trend that links larger species with shorter sleep and smaller species with longer sleep, Manger says. Some bats, for instance, routinely sleep 18 hours a day. He and his colleagues are now toying with the idea that sleep duration might be related to a daily time budget. Bigger animals may sleep less as they need more time for tasks to sustain their size. Building and maintaining an elephant body, Manger posits, may simply take more dining time than maintaining a little bat body.

Previous studies have indicated that large mammals tend to slumber less than smaller ones, possibly because they need to spend so much time eating, Sam Wong writes in The New Scientist. But even among large animals, elephants are comparatively light sleepers; giraffes, for example, sleep about five hours per day.

Various studies have theorized that sleep clears toxins out of the brain , and gives mammals a chance to reset their brains for a new day of learning and memory formation. But if this were true, how could elephants maintain their extraordinary memories? The elephants also wore a collar with a gyroscope attached to it, which told the researchers whether they were standing up or lying down.

Each elephant slept lying down on only 10 of the 35 days. This finding implies that the animals spent very little time in rapid-eye-movement REM sleep, the stage when we have vivid dreams that is thought to be important for memory consolidation.

During REM, the muscles usually relax, making it impossible to remain standing. Either elephants only experience REM every few days, or they can enter this phase in short bursts of 5 to 10 seconds while standing, as birds do, says Manger. Alternatively, like whales and dolphins, they may not need REM at all.

Combining this with a GPS collar and gyroscope — which measured bodily movements in the x, y and z planes , we made four really interesting observations:. Existing research done on captive elephants found that they slept on average between four and six hours a day. A large elephant needs to eat around kg of low quality food daily. This leaves little time for sleep. One of the specialisations in the elephant brain are orexin neurons of the hypothalamus.

If not, they keep you awake. This balance and the quality of the diet explains the trend for larger mammals to sleep less, or herbivores to sleep less than carnivores and omnivores like humans. The elephant data supports this emerging idea in sleep research, and helps explain why the elephant sleeps so little.

In captivity, elephants spend much of their time asleep lying down, but they also sometimes sleep standing.