Alert Dolphins Can Sleep With Only Half Of Their Brains Shut Down [Study]

Dolphins can pull an all-nighter with no problem, a new study contends.

Specifically, dolphins can remain alert for long periods of time because they rest with only half of their brains turned off according to the data from the National Marine Mammal Foundation.

Scientists claim that unihemispheric sleep by dolphins came about through natural selection.

The L.A. Times explains that the study tested two dolphins’ ability to use their echolocation ability “which functions like a submarine’s sonar system — to find targets randomly spread throughout the pen.”

The dolphins were able to find the targets (and get rewarded with fish) in three sessions — each lasting five days — with a high degree of accuracy. The female dolphin being tested even achieved near-perfect performance for 15 straight days without a break for a full nap.

The study, as published in the PLOS ONE journal, suggests that the dolphins’ brains stay awake so they can continue to surface to breathe while swimming under water and watch out for hostile sea creatures even given the poor visibility in the ocean. The study explains that “during echolocation, dolphin produce clicks and listen to returning echoes to determine the location and identity of objects.”

The male dolphin in the study had about a 86 percent success rate while the female, who hung in there for 15 days without crashing, was at 99 percent.

The study concludes that “our results demonstrate that dolphins can continuously monitor their environment and maintain long-term vigilant behavior through echolocation.”

The scientists have not yet determined how long the dolphins can “maintain continuous vigilance” without shutting down both brain hemispheres and going completely to sleep. That will undoubtedly be a subject for a future study.