Sleeping fish without eyes, because there is a 2-part brain is working to open the system STANDBY mode, similar to just float and prevent disasters. In other systems the section.
Fish sleep without sleep because the brain operates two alternates. STANDBY mode is similar to the system just floating and defense. The other system to rest
Fish sleep without your eyes because the brain 2 parts work alternately, similar to STANDBY mode open system and a floating security. The other system is rest.