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 ...

A new Nature Communications study has tracked these lulls in cassiopea jellyfish, which belong to a 500 million year-old ...

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 ...