A protective mucous cocoon surrounds this parrotfish as it sleeps in Australia's Great Barrier Reef. This layer of protection helps fend off predators so parrotfish can get a good night's rest.

You’re staring at your aquarium. It’s late. Everything is quiet. And there’s your fish, floating calmly, fins moving slowly, eyes wide open. Are they... asleep? Or just zoning out? Fish don’t come ...

Sleep is one of the most essential parts of being human. Catching some Z’s is important for daily functioning. As adults, we've got to get in about eight hours a day, according to the Sleep Foundation ...

There are tens of thousands species of fish around the world, whether it's in an aquarium, river, lake, or ocean. Like all animals (and humans), every single one needs some form of rest for cognitive ...