Why do humans spend a third of their lives sleeping? Why do animals sleep? Throughout evolution sleep has remained universal and essential to all organisms with a nervous system, including invertebrates such as flies, worms, and even jellyfish. Why animals sleep despite the continuous threat of predators, and how sleep benefits the brain and single cells still remains a mystery.
Click here for original story, How do we know we’re tired? PARP1 protein acts as antenna, signaling the brain that it’s time to sleep and repair DNA
Source: Phys.org