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Sleeping Fur Seals

June 13, 2018

How fur seals’ unusual pattern of REM sleep helps sleep researchers.



Sleep secrets from fur seals. I’m Bob Hirshon and this is Science Update.

REM, or Rapid Eye Movement, sleep comes right after our deepest sleep periods: our brains warm and we experience vivid dreams. Many scientists believe REM helps us learn or regulates mood. But by studying the unusual sleep patterns of fur seals, UCLA researcher Jerome Seigel and his colleagues have found a simpler explanation: they argue in the journal Current Biology that REM activity heats our brains, so we’re less groggy.


It kind of gets the brain fully functional in preparation for waking.


Fur seals have sleep cycles like us when they’re on land. But while living at sea, they sleep with just half their brains at a time to stay alert and keep from drowning. And they then stop having REM sleep. Why? Siegel says that since they’re never fully unconscious, fur seals at sea don’t need the kickstart that REM otherwise provides. I’m Bob Hirshon for AAAS, the Science Society.