It is difficult to tell what dolphins look like when they sleep, because they are not easy to be noticed when they sleep. When they sleep, they are very different from humans. When dolphins sleep, they only close one eye and open the other. Researchers have done special research on this state of dolphins, and people have found that when they open one eye and close one eye, one side of the brain is in a state of rest, while the other side is in a state of waking. Therefore, when they sleep, they will also keep moving and alert.

It is difficult to tell if they are sleeping without professional testing. However, some dolphins, when they reach a very safe place, will close their eyes and rest, and float in the water instead of swimming.

As mentioned above, dolphins sleep alternately with their left brain and right brain, so their sleeping time is not fixed. Some dolphins sleep during the day, and some dolphins sleep at night. No matter during the day or night, they usually don't stop moving when they rest. This can not only ensure that they are swimming all the time, but also ensure that they can know the surrounding environment anytime and anywhere, so as to avoid injury and death.