These penguins sleep for mere seconds

Nearly all animals need some form of sleep to survive, but not all of them sleep in the same ways as humans. Take chinstrap penguins (Pygoscelis antarcticus), the adorable two-foot-plus waddling birds named for the distinctive and dignified black stripes at the bottoms of their heads, which are indigenous to the islands and shores of the Southern Pacific and Antarctic Oceans.

Now a new study in the journal Science reveals that chinstrap penguins have a very unique way of sleeping. Instead of getting six-to-eight hours at night like humans, chinstrap penguins sleep thousands of times per day in four second spurts — but accumulate a daily 11 hours of sleep in the process.

Researchers from France, Germany and South Korea learned this by studying 14 chinstrap penguins sleep patterns with an electroencephalograph, which measures brain activity. While the chinstrap penguins swam in the ocean or nested on King George Island, which is near Antarctica, they regularly faced threats such as aggression from other penguins or predatory birds like the brown skua pursuing their eggs. As a result, sleeping for lengthy periods can be risky, so they evolved an ability to enter rest states in spurts of up to four seconds. This results in chinstrap penguins sleeping more than 10,000 times each day. As the authors concluded, "The investment in microsleeps by successfully breeding penguins suggests that the benefits of sleep can accrue incrementally."