Do bats close their eyes while sleeping?

No, bats do not close their eyes while sleeping. They have a unique adaptation that allows them to sleep with their eyes open. Bats have a specialized structure in their eyes called the nictitating membrane, which is a transparent third eyelid that can be drawn across the front of the eye. When a bat is sleeping, it will pull the nictitating membrane over its eyes to protect them from damage while still being able to sense light and movement. This allows bats to remain vigilant and quickly respond to any potential threats or changes in their environment, even while they are asleep.