Contrary to the seemingly relaxed seals basking on the shore, recent research reveals that elephant seals, for most of their lives, sleep merely two hours per day, in brief intervals, while submerged.
Among all marine life, elephant seals vie for the title of the mammal that sleeps the least each day.
Who sleeps the least in the world? At present, African elephants indisputably hold this record. However, seals are not far behind, as they too rest minimally.
Typically, they indulge in 10-minute sleep sessions while diving, often dreaming and spiraling when they are deep underwater.
Occasionally, they opt to sprawl on the shore for relaxation or a brief snooze.
The researchers’ burning question: When do elephant seals sleep? “For many years, a pressing question about elephant seals has been their sleep timing. We hypothesized they sleep while in the water, ceasing to swim and instead allowing the water to carry them as they slowly sink. However, this was uncertain.
Now, we can confirm that seals sleep during dives. We have also found that they sleep significantly less compared to other mammals,” stated Daniel Costa, a professor and marine ecologist at the University of California Santa Cruz.
To execute this study, 13 young females were equipped with neoprene caps to secure the sensors attached to their heads for monitoring brain waves. Real-time recordings, accelerometers, and other tools were also employed to track the seals’ movements.
“We devoted considerable time to observing seals sleep. Our team supervised the seals involved in the study to ensure they seamlessly reintegrated into the colony and exhibited natural behavior,” elucidated Jessica Kendall Barr, one of the researchers.
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