Sleep in fish may look different from humans, but rest is essential for survival. Here’s what experts have to say about fish sleep. A protective mucous cocoon surrounds this parrotfish as it sleeps in ...

Sleep is one of the most essential parts of being human. Catching some Z’s is important for daily functioning. As adults, we've got to get in about eight hours a day, according to the Sleep Foundation ...

A large group of yellowfin tuna swimming off the coast of Italy. Like all fish, they sleep, but it’s not like human sleep. Giordano Cipriani/The Image Bank via Getty Images Michael Heithaus, Florida ...

Just like humans, Betta fish sleep at night. "When sleeping, they become still, with their eyes open because of their absence of eyelids. Betta fish may lose their color while sleeping (it's their ...

Every evening, after twilight gives way to dark, hordes of marine creatures — from tiny zooplankton to hulking sharks — rise from the deep to spend the night near the surface. They revel in the upper ...

Melatonin controls the body clock -- high melatonin levels make us feel tired in the evening. However, the hormone also plays an important role in animals' biological rhythms. Artificial light at ...

Betta, or Siamese fighting, fish are among "the most popular freshwater aquarium fish in the world," PetMD reports. Native to southeast Asia, this species is known for its range of vibrant hues. There ...