In humans, nodding off for a few seconds is often inconvenient (say, during a lecture) or dangerous (think driving a car). But these lapses of drowsiness can also be beneficial. A new study published on Thursday finds that chinstrap penguins snooze thousands of times per day, accumulating their daily sleep requirement of more than 11 hours in short bursts averaging just four seconds. Researchers suspect that flightless birds might have evolved this trait because they must refuel while safeguarding eggs and chicks from predators.
A team of scientists led by Paul-Antoine Libourel of the Lyon Neuroscience Research Center in France analyzed 14 chinstrap penguins nesting on King George Island in Antarctica, recording both their physical movements and brain activity using accelerometers and scalp electrodes. They found that the critters produced slow brain waves every few seconds, indicating they were dozing. During those brief naps, the penguins’ heart rates remained steady, and their body temperatures didn’t dip.
The scientists theorized that the drowsy bursts helped penguins “rest while guarding,” allowing them to remain alert to potential threats, such as gull-like brown skuas that can snatch a parent’s egg or young chick. The researchers also noted that chinstrap penguins slept most frequently at the center of their colonies, where they’re safe from terrestrial predators and other penguins jostling for space.
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While it’s true that many animals — including humans — doze in bursts, the penguins’ staccato pattern is unique. It could reflect the stress of their environment, writes co-lead author Christian Harding in an opinion piece for Science, or it could be an evolutionary adaptation that allows the birds to conserve energy and remain vigilant to possible dangers. “Penguins might be the reigning monarchs of fragmented sleep,” he writes, “but we shouldn’t assume that all animals sleep this way.”
Indeed, researchers have long suspected that some animals, including mice and pigeons, doze in short bouts, but this latest study puts them to shame. The scientists who conducted the chinstrap penguin research have yet to study whether other species have similar sleep patterns. In the meantime, sleep experts who weren’t involved in the study are weighing in: “The data might be one of the most extreme examples of how the incremental nature of sleep can accrue,” write Dr. Vladyslav Vyazovskiy and Professor Christian Harding at the University of Oxford in an independent opinion piece. “The idea that animals spend most of their time asleep, waking up occasionally to perform certain tasks and then going back to sleep, might be the most realistic description of how we all operate.” (Click to read about the strange way jellyfish get sleepy.) 2015 MASHABLE. All rights reserved.