20 Useless Facts You Probably Didn’t Need To Know

18. Dolphins Sleep With One Eye Open

At least you can shut both eyes at night and drift off in a cosy, warm bed.

Dolphins aren't so lucky. Instead of shutting down completely, those cutesy sea creatures humanity finds so endearing only let half their brains rest at the one time. There's a reason for this: mindful of predators and drowning if they don't regulate their breathing, dolphins use the 'awake' side of their brain to feed information to the 'sleeping' part.

That's clever, and it makes the fact humans drool all over the place, snore and likely talk gibberish more embarrassing. Even more impressive, when scientists from the U.S. Navy Marine Mammal Program conducted experiments to see if sleep deprivation affected Flipper and pals, they found no negative effects.