Dolphins Can Stay Awake for at Least Two Weeks

Bottlenose dolphin mother and calf. Photo credit: NOAA.

New research shows that dolphins can stay awake for at least 15 days in a row without experiencing fatigue, or other negative side effects.

To put this in perspective, human research subjects have been able to stay awake for only eight to 10 days, and all experienced progressive deterioration in concentration, motivation, perception and other mental processes as the period of sleep deprivation increased.

Dolphins can stay awake for this long because they sleep with only half of their brain at a time.  This process, called unihemispheric sleep, was thought to have evolved as a way to allow dolphins to continue breathing at the surface while resting.

Brian Branstetter from the National Marine Mammal Foundation and colleagues studied two bottlenose dolphins (Tursiops truncatus), one male and one female, and found that they could use echolocation with “near-perfect accuracy” for up to 15 days.  Both dolphins showed no signs of fatigue for five days, and the female continued other tasks for 10 additional days.

“These majestic beasts are true unwavering sentinels of the sea.  The demands of ocean life on air breathing dolphins have led to incredible capabilities, one of which is the ability to continuously, perhaps indefinitely, maintain vigilant behavior through echolocation” said Branstetter.

The research was published in the journal PLoS ONE on October 17: Dolphins Can Maintain Vigilant Behavior through Echolocation for 15 Days without Interruption or Cognitive Impairment.

Bottlenose Dolphin. Photo credit: NASA.

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