Dolphins alternate which side of their brain is asleep and awake every 2 hours. This way, each side gets an equal amount of rest. [2] X Research source Not only is keeping one eye open important for breathing, but it also helps dolphins stay alert for danger.
Normally, a dolphin needs to surface for air every 15 to 17 minutes; however, they’ll surface less often when asleep because only one side of their body is awake. [4] X Research source Dolphins have to be partially conscious at all times, even when they’re sleeping; otherwise, they may drown. [5] X Research source
Dolphins are strategic about what side of their brain sleeps first. A dolphin must be looking inside and outside of the pod at all times, so the pod will communicate with each other to see who’s “on the lookout” for their first shift of rest. Then, they’ll switch positions.
These marine mammals can stay awake for at least 15 days if they have to—how amazing is that?[8] X Trustworthy Source PLOS ONE Online peer-reviewed, open access scientific research journal Go to source
