Jellyfish and sea anemones, despite lacking brains, show sleep behavior similar to that seen in humans, according to a new study published in Nature Communications. Researchers found that these simple marine animals, like jellyfish, experience periods of rest that align closely with human-like sleep, offering new insight into how sleep functions in creatures with nervous systems but no centralized brain. The study revealed that the upside-down jellyfish (Cassiopea andromeda) sleeps for about eight hours daily, primarily at night, with a short rest during the day. The starlet sea anemone (Nematostella vectensis), which was studied in a lab setting, also showed...