Northern Elephant Seals migrate 12,000 miles a year while sleeping only two hours a day.

A 2023 study published in the journal Science, led by researchers from the University of California, Santa Cruz, revealed that Northern Elephant Seals (Mirounga angustirostris) survive on less than two hours of sleep per day during their seven-month migrations. This is one of the shortest sleep durations of any mammal, rivaling only African elephants. The research team used non-invasive EEG sensors and motion trackers to monitor brain activity in wild seals for the first time.While at sea, these seals perform 'sleep dives' that reach depths of nearly 2,500 feet. At these depths, they are safe from surface-dwelling predators like Great White sharks and Orcas. As they descend, their brain activity transitions into REM sleep, causing their muscles to relax and their bodies to spiral downward in a controlled drift. Each nap lasts only about 10 to 15 minutes, occurring multiple times throughout the day to reach their daily total.This adaptation is crucial because the seals spend up to 200 days at a time in the open ocean without coming to shore. By comparison, when these seals are on land during breeding season, they sleep for more than 10 hours a day. The ability to switch between these extreme sleep states demonstrates a remarkable evolutionary adaptation to the high-risk environment of the North Pacific Ocean.