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The Small Sleep

Some elephants can go forty-six hours without sleeping.

An elephant.

Photo: John Hiliard (Flickr)

Scientists are studying the links between elephant survival and how much they sleep.

When people go without sleep, they can experience impaired motor functions, mood swings, and affect your memory. For some wild African elephants, going without much sleep is a different thing.

Short Bursts

Scientists discovered some wild African elephants hardly sleep. They get maybe two hours of sleep per night, usually in short, twenty‑minute bursts. And it doesn’t seem to affect their memory or ability to function.

The researchers weren’t sure why the elephants get so little sleep. The two elephants that were studied are the matriarchs of a particular herd in Botswana. Matriarchs have a lot of responsibility for leading the herd to food and avoiding predators. So, they may not have the luxury of getting much sleep.

Large Herbivores

The herd regularly traveled nearly twenty miles per day. And despite the journeys, the matriarchs would sometimes stay awake for forty-six hours straight.

It is true that in general, animals that are on the larger side, who are also herbivores, tend to need less sleep than smaller mammals with different diets. But elephants, apparently, get the least sleep among large herbivores.

It does seem amazing that it’s possible for an animal to be able to do all those things on a very low amount of sleep. But other animals such as dolphins and seals, are known to function well with very little sleep.

One theory for why these animals can do this is it’s probably an evolutionary adaptation. Animals need the ability to keep moving to find food and evade predators.

Thank you to Jerome Siegel of UCLA for reviewing this episode!

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