Nature & Environment

Crocodiles really do sleep with one eye open

By T.K. Randall
October 23, 2015

Image: Nile Crocodile
Credit: Leigh Bedford / CC BY 2.0 (adapted) Scientists in Australia made the discovery while observing the round-the-clock behavior of juvenile crocodiles that were being kept inside a special aquarium lined with infrared cameras.

During the study the animals showed a tendency to keep one of their eyes open while sleeping when there was a human in the same room with them - a behavior which seemed to suggest that they were able to continue looking out for potential threats even while unconscious.

The scientists concluded that crocodiles may only sleep with one brain hemisphere at a time, a behavior that has also been observed in birds, dolphins and several other species."To me, the most exciting thing about these results is they provide some evidence to think that the way we sleep might be novel, in an evolutionary sense," said senior author John Lesku.

"We tend to think of our sleep as the norm: a behavioural shutdown that is a whole-brain affair."

"And yet if birds sleep unihemispherically, and if crocodiles and other reptiles that engage in unilateral eye closure - if it turns out that they are also also sleeping unihemispherically, then suddenly our sleep becomes unusual."

Source: BBC News

Tags: Crocodiles, Sleep