14 DAY TRIAL // In a new study in the Journal of Experimental Biology, wildlife researchers with Australia's La Trobe University explain that, as weird as this might seem, the fact is that crocodiles more often than not sleep with one eye open.
Like dolphins and other marine mammals, they seem to also rest just half of their brain at a time. This means that the eye that stays open isn't just idling, but is instead connected to fully functional neurons, ready to kick into gear, should prey or any potential threats pop up.
While it's not always that crocodiles go to bed and leave one eye wide open to stand guard, the La Trobe University research team say the reptiles are more likely to display this peculiar behavior if humans happen to be nearby.
“The researchers found that crocodiles were more inclined to sleep with one eye open when humans were present, and that the open eye was always directed towards the humans,” reads a report detailing the team's investigation.
Apart from dolphins and other aquatic mammals, this habit of resting just half a brain at a time has so far also been documented in some birds. Scientists call this behavior unihemispheric sleep. For long, they thought it to be an oddity.
Now that it's also been documented in crocodilians, however, specialists are more inclined to think that this might actually be the norm in the animal kingdom and that we humans and our bihemispheric deep sleep are the odd ones out.