Do Dolphins Sleep?

Have you ever asked yourself do dolphins sleep, or how? To be perfectly honest, I have not. In fact, this question was brought up by a 6-year-old kid to me last month.

We all know that dolphins (and whales) are mammals just like us. They are warm blooded and give birth to live young. In addition, they have similar bone structures.

The biggest difference is their respiratory system that allows them to spend 30 minutes or more without needing to surface for air! Many of us must be thinking they have HUGE lungs! In fact, no, the size of lungs does not determine the amount of oxygen that can be stored. Dolphin lungs contain more air cells and have two layers of capillaries compare to human lungs which has only one layer. This increases the surface area of the lungs and therefore increases the efficiency of gas exchange.

Now, back to the initial question. For mammals on land, breathing is an unconscious effort. Our body takes in air automatically. However for dolphins, it has to be a conscious effort because of their undersea environment. In other words, they have to actively decide when to breathe. It is not feasible to be totally unconscious because they need to wake up in time to breathe. Thus this is a problem because brains of a mammal need to enter into an unconscious state from time to time so that our brains can function correctly.

Scientists have studied and discovered that the solution for dolphins to sleep is to let half of the brain sleep at a time. Therefore, one half of the brain goes to sleep at one time and the other is fully aware of its surroundings. Scientists have also discovered that dolphins are in this state approximately 8 hours a day! This is the exact amount of sleep that we are advised to have as well!

Hence, the dolphins are not completely unconscious but still get the right amount of rest it needs.

How amazingly unique God has created all creatures so that they can adapt and survive in different climates and surroundings. I do think that dolphins are one of the most beautiful animals on Earth. Until today, their 'smile' still melts my heart like butter =)

Reena