HowDoWhy

 Yep! Dolphins and whales are mammals and all mammals sleep. Aside from living in water, one of the things that distinguishes us from our aquatic cousins is how we breathe. Humans don’t have to think about breathing. You can, if you choose, hold your breath or elect to inhale or exhale. But if you stop thinking about breathing, you’ll still go right on doing it even when you’re completely unconscious or asleep. We are unconscious breathers.

Dolphins and whales differ from us in that they are conscious breathers. They choose when to breathe at all times. It’s an important distinction. Imagine if you were to doze off underwater. Eventually, your body is going to inhale with disastrous results! The same would happen with dolphins and whales if they weren’t designed to breathe consciously.

Now if you’ve put two and two together, you have probably concluded that sleeping is the same as being unconscious so how could a dolphin possibly sleep if it has to consciously breathe?! It’s a neat trick of nature.

A dolphin sleeps half a brain at a time! That’s right, dolphins or whales will shutdown one hemisphere of their brain during “sleep” and repeat the process with the other half later. They will tend to remain near the surface while doing so to minimize effort in breathing. During these rest cycles, they are likely in a semi-conscious state much like we are shortly before we truly fall asleep. They can still rapidly wake up, respond to external stimulus and react to danger if needed unlike us when we’re completely asleep.

An interesting note on dolphin sleep - Just as our experts have been suggesting to us for years, dolphins spend about 8 hours a day in their sleep state. If it’s good for Flipper, it’s good for you!