Penguins are the champions of short naps.
In a single day, they fall asleep thousands of times, in episodes that last a few seconds, a new study shows.
Although animals have a wide range of sleeping styles, penguins by far break the record for fragmented sleep.
“It's very unusual,” said Paul-Antoine Libourel, a neuroscientist at the Lyon Neuroscience Research Center in France, who helped make the discovery.
The study was published in the journal Science.
In 2019, Libourel and his colleagues monitored sleeping animals in a remote environment: King George Island, 100 kilometers north of Antarctica.
Won Young Lee, a researcher at the Korea Polar Research Institute, invited the group to accompany him to the island, where thousands of pairs of chinstrap penguins gather in nesting colonies to raise their chicks. In December 2019, researchers fitted the penguins with electrodes and other sensors that recorded their activity for up to 11 days.
The birds divide their time between swimming in the ocean and staying in their nests to keep their eggs and chicks warm. Between each trip to the sea, which took about 9 hours, the penguins spent 22 hours on average taking turns caring for their chicks.
While in the water, the birds spent only 3 percent of their time sleeping on the sea surface.
When the penguins returned to their nests, their brain waves slowed down to a pattern typical for sleeping birds—but only for a few seconds. They woke up again, only to go back to sleep. The birds completed this cycle 600 times in one hour.
Humans can also experience this type of microsleep, although usually only after not getting a good night's sleep. But for chinstrap penguins, microsleep is the norm.
Libourel speculated that their sleep patterns reflect the extreme conditions in which they snooze. Penguin colonies are noisy and crowded, with birds constantly going to sea and back. The habitats are also dangerous.
The fact that penguins manage to sleep so much despite all these disturbances suggests to Libourel that microsleep offers some essential benefit.
However, Vladyslav Vyazovskiy, a neuroscientist at the University of Oxford who was not involved in the study, questioned how much the penguins benefit. He argued that we might be seeing the dream backwards. It could be the default setting of the animal brain, and scientists should be trying to explain why animals wake up when they do.
“Basically, you spend your life sleeping and only wake up when necessary,” Vyazovskiy said.
By: CARL ZIMMER
BBC-NEWS-SRC: http://www.nytsyn.com/subscribed/stories/7026165, IMPORTING DATE: 2023-12-12 18:50:06
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