OThey call it a Napoleonic nap. Ten to twenty minutes of restful sleep, and you’re ready to invade Austria or, more modestly, to settle for four-hour nights. Nothing to brag about though. “Napoleon, little player”even having fun Paul-Antoine LibourelCNRS research engineer at the Lyon Neurosciences Research Center.
The scientist signed, Friday 1er December, in the magazine Science, an article with quite astonishing results. He and his collaborators found that in Antarctica, the chinstrap penguin slept in sessions averaging four seconds. Lots of sessions, it’s true: the bird has around 10,000 sessions per day for a total of eleven hours of daily sleep. Observations that explode all the records recorded so far.
This record finding firstly reflects a technical, human feat. A few years ago, the engineer developed a miniature “polysomnograph”, which earned him the CNRS crystal medal for innovation in 2021. On a card measuring 2 centimeters by 1 centimeter, he can record the brain, heart, muscle and eye activity of an animal. “Like a sleep clinic but miniaturized”, he summarizes. Added to this is a second device, barely larger, a mini-GPS, capable of recording the position of the animal but also its movements, the outside temperature and the pressure. Finally, it can store this information for a few days or even a few weeks. A little gem that caught the attention of Professor Won Young Lee at the Polar Research Institute in Incheon, South Korea. This marine biologist studies Antarctic birds and wanted to understand what the blinking of the eyes he observed in chinstrap penguins corresponded to. “He contacted me and we decided to collaborate”says the Frenchman.
Some obstacles presented themselves to them. First, ensure that the devices, stuck on the birds, would withstand extreme temperatures and dives several hundred meters deep. Then equip the animals. And, finally, hope to recapture them to collect the data. Of the twenty penguins equipped, nineteen were found and fourteen provided all the desired information, namely eleven full days, recorded in December 2019. With, at the end, impressive revelations.
Starting with the extreme brevity of “naps”: 75% of episodes last less than ten seconds, for an average of four seconds. Sequences during which both cerebral hemispheres often sleep, as in humans, but also frequently only one hemisphere, the other remaining awake. Another lesson: no night, no day, but a sort of “perpetual drowsiness”, constant alternation between wakefulness and sleep, in a lying or standing position, it doesn’t matter.
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