These Guys Get by on 2 Hours of Sleep a Day

Researchers matched northern elephant seal brain waves with diving patterns to monitor how they sleep
By Steve Huff,  Newser Staff
Posted Apr 21, 2023 10:39 AM CDT
These Guys Get by on 2 Hours of Sleep a Day
Elephant seals on a beach.   (AP Photo/Nick Ut, File)

If you're still drinking coffee and blinking sleep out of your eyes, you might feel sympathy for the northern elephant seal. NPR reports that in a newly-published study, researchers found the huge mammals—known for the way the males' noses resemble elephant trunks—sleep less than just about any other member of the animal kingdom, clocking in at about two hours a day. Ecophysiologist Chris McKnight at Scotland's Sea Mammal Research Unit tells NPR that these animals have some truly extreme traits in general. For example, they really are massive: Adult females weigh over 1,300 pounds and males can crush the scales at more than two tons. McKnight, who didn't take part in the study, says researchers did "an exceptional job" gathering info, considering they had relatively limited access to the seals.

According to Science News, only African elephants can come close to matching the big seals' ability to snatch a quick nap, and actual elephants doesn't have to worry about circling sharks. A Science study published Friday says the northern elephant seals' two hours a day often come in 20-minute increments, while foraging at sea for months, around the clock—and they can dive as deep as 3,000 feet for between 10 and 30 minutes at a time. "So there's a bit of a conundrum," explains McKnight. "If you're diving all the time, if you're spending 90% of your time at sea underwater without access to air, when the hell do you sleep?"

University of California San Diego ecophysiologist Jessica Kendall-Bar and fellow researchers fitted seals with specially-designed EEG caps to measure brain activity while the big creatures hunted for food. They matched brain activity to the seals' diving patterns to gather data on how they sleep. Kendall-Bar tells Science that northern elephant seals differ from other sea mammals like dolphins, who manage to sleep with one side of their brain at a time. In her opinion, "it’s pretty cool that elephant seals are doing this without [one-sided] sleep." She continues that the seals are "shutting off both halves of their brain completely and leaving themselves vulnerable." Kendall-Bar also notes that it is "important to map these extremes of [sleep behavior] across the animal kingdom to get a better sense of the evolution and the function of sleep for all mammals, including humans." (More scientific study stories.)

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