Weird Chinstrap penguins sleep over 10,000 times a day for just 4 seconds at a time

Chinstrap penguins are one of nature's most extreme nappers, snatching more than 10,000 microsleeps lasting up to four seconds long every day, according to a new study.

The penguins, which live in breeding colonies each containing tens of thousands of individuals, must remain constantly vigilant against threats to their nests from predatory skua birds and hostile colony neighbors. 

The result is a sleeping schedule warped beyond all recognition — placing the penguins in a state somewhere between wakefulness and sleep that culminates in 11 hours of snoozing time per day. The researchers behind the study published their findings Dec. 30 in the journal Science.

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"It shows nicely at what point sleep is constrained by natural selection processes," Paul-Antoine Libourel, a researcher at the Lyon Center for Research in Neuroscience in France, told Live Science. "Animals face a clear tradeoff between sleeping and its benefits while not being vigilant, and being awake but with the physiological cost of not sleeping. These penguins found a way to gain the advantage of sleeping while also remaining vigilant to protect their eggs."

Named after the thin black strip that runs under their beaks, chinstrap penguins (Pygoscelis antarcticus) live on islands all the way around the South Pole. During the nesting season, males squat on eggs to provide protection and warmth while females leave on long hunts. In the chaotic and noisy environment of the colony, any sleep is welcome — but it comes at a cost of decreased watchfulness.

To study how the penguins managed the careful balancing act, the researchers studied the sleep patterns of 14 penguins out of a colony of 2,700 breeding pairs on King George's Island off the coast of Antarctica. After surgically implanting electrodes into the penguins' brains and connecting them to data loggers placed on their backs, the researchers released them back onto the island.