How do Dolphins sleep?

Dolphins have to be conscious to breathe. This means that they cannot go into a full deep sleep, because then they would suffocate. Dolphins have “solved” that by letting one half of their brain sleep at a time. This has been determined by doing EEG studies on Dolphins. REM (Rapid Eye Movement) sleep, usually associated with dreaming has been recorded only very rarely. Some scientists claim Dolphins do not have REM sleep at all. A Dolphin’s behavior when sleeping/resting depends on the circumstances and can vary within different species of Dolphins, and possibly on individual preferences. They can either: swim slowly and surface every now and then for a breath which is the pattern for the Hawaiian Spinner Dolphins; rest at the surface with their blowhole exposed; or rest on the bottom (in shallow water) and rise to the surface every now and then to breathe.