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.

Do fish with no eyelids sleep? Given that they spend their entire lives submerged in water, this is a reasonable question to ask. The short answer is yes, fish do sleep. But the way they sleep differs ...

Tom has a Master's degree in Journalism. His editorial work covers anything from archaeology and the environment to technology and culture. Tom has a Master's degree in Journalism. His editorial work ...

Contrary to common belief, not all vertebrates regulate their sleep-wake rhythm in the same way. University of Basel researchers have discovered that some fish – unlike humans – do not need orexin to ...

Fish don’t have eyelids. They don’t curl up in beds or snore, so it’s easy to assume they just keep swimming forever without rest. But they do sleep—it just looks very different from how we do it.