Why do bats hang upside down while sleeping? Scientists' answer might surprise you.

When bats are not flying, they often hang upside down, for instance, on cave ceilings. But why do bats sleep upside down? This is discussed by Live Science.

Biologist Tara Hochhoffer believes that the reason bats sleep upside down is likely a result of how these unique flying mammals evolved to take to the air. When bats began their transformation from terrestrial mammals to flying creatures, they initially glided through the air like flying squirrels.

According to biologist Alexander Lewis, the ancestors of modern bats may have climbed high trees and glided between trunks, which led to the development of strong limbs. The powerful forelimbs of gliding bats eventually evolved into wings over time.

Hochhoffer notes that since bats lack hollow bones like birds, they do not generate as much lift during flight. As a result, bats often hang upside down to jump and take off.

Most people would find it difficult to hang upside down like bats do. However, these animals find it much easier due to the evolution of their muscles, tendons, and claws.

Scientists explain that when a bat finds a roosting spot, it contracts the muscles attached to its claws, which opens them. When the claws contact the roosting surface, the bat relaxes its body, allowing its weight to pull on the tendons connected to the claws.

As a result, the claws grip the roosting surface, and the bat's body weight keeps the claws closed. In other words, bats expend minimal energy to hang upside down, as their bodies are relaxed and gravity does the work for them.

Unlike humans, bats can hang upside down for extended periods. While this position can lead to blood pooling in a human's head, causing health issues over time, the compact size of a bat allows its heart to easily pump blood throughout its body.

According to Hochhoffer, when bats adapted to hanging upside down during sleep, this new lifestyle led to the emergence of several other traits in these mammals. For example, bat skeletons evolved to be lightweight, which aids in flight.

When bats hang upside down in hard-to-reach places, it also protects them from predators such as owls, hawks, and snakes.

Scientists state that when bats are on the ground, they can still take off from a standing position, but it is more challenging than starting flight from a hanging position.