Generally, the dolphin brain is larger than a human's is, and the dolphins use a much larger percentage of their brain than do humans. Dolphins have an incredibly complex system of communication, using sonar and an exchange of holographic acoustic images. Like sight to humans, sound and vibration are central to dolphins. Their frequencies range far beyond the human spectrum of sound. In addition, by using their complex sonar, they can examine objects with incredible detail.
Dolphins never sleep.
They are conscious all the time. Unlike humans whose breathing is automatic, dolphins make a decision to breathe. They also choose sex. Unlike animal species who breed from instinct, dolphins have sex for procreation and for pleasure. They enjoy their sexuality freely.