Why do bats sleep upside-down? Bats sleep during the daytime. Hanging upside down in caves, underneath bridges, or in hollowed out trees helps to conceal them from predators. It is also the perfect position for the bats to take off from, because they can’t lift off into flight like birds, but need to fall into it. Lastly, hanging upside down conserves energy. In JungleWorld, look up to see our large fruit bats hanging from the trees. | Bronx Zoo