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.

Turns out jellyfish and sea anemones – among the ancient creatures with a nervous system instead of a brain – have a very similar sleeping routine to our own. A new study published in Nature ...

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 ...

Jellyfish sleep around eight hours a night, take short daytime naps, and compensate for lost rest,all without having a brain. These behaviors, revealed in a new study, suggest sleep may be far more ...

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 ...

Sleep is a universal biological state that allows all animals, from mammals to amphibians, fish and even insects, to restore ...

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 ...

Sleep is one of life’s most universal behaviors. Despite its ubiquity, it’s also one of the most mysterious. Humans spend ...