How taking up to 10,000 naps a day lets chinstrap penguins keep a close eye on their chicks

Spending your nights sleeping for just four seconds at a time may sound like a form of torture but not for chinstrap penguins, who fall asleep thousands of times a day, new research finds.

- Phoebe Weston, Ian Sample

Scientists studying the birds on King George Island in Antarctica found they nodded off more than 10,000 times a day, allowing them to keep a constant eye on their nests, protecting eggs and chicks from predators. In total, the birds manage 11 hours of snoozing a day - without ever slipping into uninterrupted sleep.

"Humans cannot sustain this state, but penguins can," said the lead researcher, Paul-Antoine Libourel, from the Lyon Neuroscience Research Centre. "Sleep is much more complex in its diversity than what we read about in most textbooks."

Researchers had looked at penguin sleep in the 1980s, which involved capturing them, putting them in a shelter and watching them. They reported fragmented sleep for short periods of time, which they called "drowsiness". In the latest research, experts found that this fragmented sleep was sustained for the whole day, showing the penguins were not "nodding off" into deeper sleep.