Snoozing Sharks?

It used to be assumed that sharks didn't sleep. It was argued they couldn't sleep, as they needed to constantly move forward to aerate their gills. There has, however, been anecdotal evidence, largely from scuba divers, that some sharks do sleep. A La Trobe University (Australia) study has now produced scientific evidence that at least some shark species have regular snooze (https://www.theguardian.com/environment/2022/mar/10/sleeping-with-fishes-australian-scientists-discover-some-sharks-do-need-their-shut-eye). The La Trobe study looked at a benthic (bottom-living) species, the Draughtboard shark. Monitoring this fish's metabolism and posture, clearly revealed bouts of sleeping. There is no reason to suspect that this phenomenon doesn't also occur in more active pelargic species.