Add Yahoo as a preferred source to see more of our stories on Google. A protective mucous cocoon surrounds this parrotfish as it sleeps in Australia's Great Barrier Reef. This layer of protection ...

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 ...

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 ...