For the first time, scientists have recorded brain activity in a free-ranging, wild marine mammal, revealing the sleep habits of elephant seals during the months they spend at sea.
Elephant seals drift downwards into the ocean in a "sleep spiral" to catch up on sleep while on months-long foraging trips but are programmed not to drown, according to a new study.
Sleep is a precious commodity for people and across the animal kingdom, indispensable even as its biological purpose remains somewhat mysterious. We spend about a third of our lives asleep. But some animals get a lot less slumber - with certain species li