This pod of sleeping sperm whales were sleeping so deeply they did not notice a research vessel until it bumped into them. The whale noses sticking out of the water alerted the researchers to their presence.
It appears that the sperm whales go into a full sleep for short periods of time several times a day. It is suspected they also have shorter periods of sleep throughout the day. (Whale naps and cat naps?)
they sleep very little: just 7% of the time. That contrasts sharply with smaller beluga and grey whales, which sleep for 32% and 41% of the time, respectively. Such a meagre amount of sleep designates the sperm whales as the least sleep-dependent mammals known. (The current record-holder is the giraffe, which sleeps for 8% of the time.)
The research team was from the University of St Andrew’s, UK, and they found the sleeping whales in Chile.
Go to Nature for more info and a video.