Question: What animal sleeps with one eye open?
Answer: Dolphins. Because they must actively decide when to breathe, they have to stay continually conscious. They can’t go into a deep sleep or they’ll drown. Instead, only half their brains are asleep at a time while keeping one eye open. It’s the left eye when the right half of the brain sleeps, and the right eye when the left brain sleeps, in a process known as unihemispheric sleep.
