Dolphins sleep very differently, as they must continue to come to the surface to breathe while sleeping. With the help of our breathing reflex, humans can have prolonged periods of unconscious sleep and breathe automatically, utterly unaware of our surroundings. Dolphins cannot!.

Dolphins must remain conscious, even when sleeping, as their breathing is not automatic; It is consciously controlled. In other words, dolphins must actively decide when to breathe, so they must always be conscious of their breathing!

Dolphins only close one eye when they sleep; the left eye will be closed when the right half of the brain sleeps, and vice versa. This type of sleep is known as unihemispheric sleep, as only one brain hemisphere sleeps at a time.

Dolphins alternate which half of the brain is sleeping periodically so they can get the rest they need without losing consciousness. When sleeping, dolphins often rest motionless at the surface, breathing regularly, or may swim very slowly, close to the surface.

If dolphins slept like us, in deep unconscious sleep, they would stop breathing and suffocate or drown! They need to keep conscious breathing even when they sleep!