Cave-dwelling fish are able to thrive with minimal sleep.

Sleep is considered essential for the health of animals, including us, but some cave fish can manage to survive without it. However, cavefish appear to be healthy and have normal lifespans despite the lack of sleep.

alex keene More than a decade ago, researchers at Texas A&M University discovered the cave-dwelling Mexican tetra (Astyanax mexicanus) He seems to have hardly slept. “Some people are sleeping a little bit,” Keene said. “Many fish get zero sleep.”