Do dolphins sleep?
Due to the fact that dolphins are conscious breathers, they cannot sleep the same way terrestrial mammals sleep. One theory on sleeping in dolphins is that they alternately rest each half of their brain for 2-3 minute intervals throughout the course of the day. Dolphins have cross-ocular connections like humans do, so they may close one eye when resting the opposing side of their brain. Therefore, half of their brain remains alert, enabling them to surface when they need to breathe and constantly be aware of predators. Dolphins sleep about 30% of their day (very similar to the amount needed by humans), but they do not have an extended sleep period.
We, as humans, are involuntary breathers. This means that we do not have to think about every breath that we take. Dolphins on the other hand are voluntary breathers, and they do have to think about every breath that they take. Dolphins do not sleep like we do since they have to think about each breath and they live in the water. They could drown if they fall asleep. Basically, they shut down half of their brain at a time for rest, while the other half stays awake to breathe. They take “naps” throughout the day.
