"Sperm whales literally drift to sleep, but it's a snooze like no other, according to a recent study that found whales perform slow, rhythmic dives as they slumber.
Because these drift dives keep the whales in constant motion as they rest, scientists now think the seafaring mammals sleep with one side of their brain at a time. The two sides alternate until both are rested."
"If the only sleep sperm whales get is during these drift dives, it would be less than any mammal studied so far," lead author Patrick Miller told Discovery News.
The rest of the article can be found here, at Discovery.com