Do whales sleep?
In a way—they become quiescent, which is a resting state much like sleep. Whales and dolphins are thought to sleep with half the brain at a time, and are often observed, during quiescent periods, with just one eye open. A resting whale breathes by reflex, bobbing slowly up and down in the water to take periodic breaths. Since the whale isn’t moving much, it doesn’t need to breathe very often as it rests.
