Can you sleep with an eye open? A study from Australia has suggested that crocodiles can sleep with an eye open. Researchers discovered that the reptiles can use ‘unilateral eye closure’, which allows them to look out for potential threats or prey when they are dozing.

During the study, researchers took three juvenile saltwater crocodiles from northern Queensland to a huge aquarium at La Trobe University. They captured the replies the whole day. They discovered that the crocodiles opened one eye when they gave artificial stimulus to the tank.

Dr. John Lesku said, “The value of the research is that we think of our own sleep as "normal" - a behavioral shutdown that is a whole-brain affair”.

The study was published in the Journal of Experimental Biology. It suggested that crocodiles can sleep with an eye open because they can switch off one side of their brain, while the other part of the brain stays active.

Lead researcher Michael Kelly, of La Trobe University in Melbourne, said the study findings were actually exciting because they were the first of their kind that involved crocodilians and could change the way the evolution of sleep is considered.

Even when the person observing left the room, the croc didn’t close its open eye and kept on looking in the same direction, just in case the person make a comeback. The crocodiles keep their one eye open and stay watchful, probably because younger crocodiles can be at risk of predators and they stay together to minimize any threat.