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 ...

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 ...

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 stay ...

Humans and other mammals cycle through distinct sleep phases. One of them is easily recognized by the darting motion of the eyes behind closed lids, giving it its name: REM (rapid eye movement) sleep.

The short answer is yes, fish do sleep. But the way they sleep differs from land-dwelling creatures. Unlike humans who have eyelids, fish don't close their eyes when they sleep. Instead, many species ...

Mammals, including humans, cycle through two sleep stages: REM sleep and non-REM sleep. A study investigating whether fish also have sleep stages revealed that the zebrafish has four sleep stages. REM ...

Researchers have discovered that some fish -- unlike humans -- do not need orexin to stay awake. This molecule was thought to be necessary for normal wake and sleep rhythms in vertebrates. Humans ...