Which came first, sleep or the brain?

In work that could help unravel the origin of sleep, an international team of researchers has shown that tiny, water-dwelling hydras not only show signs of a sleep-like state despite lacking central nervous systems but also respond to molecules associated with sleep in more evolved animals. The new results suggest that many sleep-related mechanisms developed before the brain and may have been conserved during the evolution of central nervous systems.

from Top Health News -- ScienceDaily https://ift.tt/3hToIjf