Penguins sleep 10,000 times a day

The chinstrap penguin (Pygoscelis antarcticus) on King George Island, Antarctica, takes several short naps instead of one long sleep so it can continuously watch over its eggs and chicks.

Strapback penguins take more than 10,000 naps a day, each lasting just four seconds. They sleep for about 11 hours a day, while still being able to constantly watch over their nests, protecting their eggs and chicks from predators.

This is the result of a new study conducted by expert Paul-Antoine Libourel at the Lyon Neuroscience Research Center and colleagues.

One of the main predators of chinstrap penguin eggs on King George Island is the brown skua (Stercorarius antarcticus). They often steal eggs from the outer nests, which are not protected by the parents.

Pairs of chinstrap penguins often split up, with one staying behind to guard the nest and the other going out to sea to forage. The one that stays home must constantly be on the lookout to protect the eggs or chicks from predators such as skuas or other penguins.

The team monitored 14 penguins with eggs in their nests. They measured sleep-related brain activity and changes in body posture using data loggers. The results showed that the nestlings could sleep both standing and lying down, with nearly 72% of their short-wave sleep (SWS) lasting less than 10 seconds. The parent penguins had about 600 SWS episodes per hour, a number that increased while they were incubating their eggs. The depth of sleep increased slightly around noon, when the risk of predation was likely to be lowest.