Sperm whales spend most of their time sailing lazily through the deep, only occasionally stopping to have a terrifying penis. (The ones in the video are right whales, but I assume the sperm whale is much the same.) Basically, their normal activity looks not unlike you and me sleeping. But it turns out their sleeping looks like you and me standing up! Oh, that crazy backwards undersea world.
Researchers first found a pod of vertically bobbing whales in 2008. Until then, they’d thought that sperm whales (and other whales, and dolphins) only rested one brain hemisphere at a time, keeping the other alert in case Captain Ahab showed up. But after their boat bumped right into a pack of snoozing cetaceans, they realized that whales do sleep fully in 10- or 15-minute increments. Any longer and it might be a problem that they’re fully submerged and can’t breathe.
If this is the only sleep whales get, then they have the lowest sleep needs of any known creature, sleeping only 7 percent of the time. Which is maybe not surprising, given the whole thing where their most active day looks like a human nap.