Sharks must keep the water moving over its grills for them to get oxygen. It’s thought for long that sharks have to move constantly for them to survive. This may mean that sharks can’t stop being mobile and thus, no time to sleep. Is this a myth?
After years of research and studies among sharks, shark sleep is still a little bit of mystery.
Though the question of how a shark sleeps will depend on how sleep is defined. According to Merriam-Webster online dictionary, it defined sleep as the natural periodic suspension of consciousness during the powers of body are restored.
There is no certainty that sharks can suspend its consciousness but, it can be possible.
Sharks have to swim to receive oxygen to their body as what mentioned. This may seem to have restful and active periods instead of undergoing deep sleep like what humans doo. It is more like sharks are “sleep swimming” with some part of their brain is “at rest” mode or less active while the shark is swimming.
No Concrete Evidence
There’s at least a study indicating that the spinal cord of the shark coordinates its swimming movements rather than its brain. This would be a sensible theory for sharks to swim while they’re unconscious.