Dolphins actually sleep for very short periods of time(1-2 minutes at a time), because if they slept longer, they would forget to breathe. They don't involuntarily breathe like we do(safety mechanism, like while we sleep), they have to consciously think about it. It kind of goes like this: swim swim swim, surface and breathe, swim swim swim This is how the Sea World people explained it anyway, and I would at least hope they would be correct about their own dolphins