Fish Rest, but They Do Not Sleep the Way We Do

Do fish sleep? NOAA’s National Ocean Service answers with care. While fish do not sleep in the same way that land mammals sleep, most fish do rest. Research shows that fish may reduce their activity and metabolism while remaining alert to danger. NOAA suggests these periods may perform the same restorative functions as sleep does in people, and it puts the word sleep in quotation marks when it applies it to fish. How they rest varies. Some fish float in place. Some wedge themselves into a secure spot in the mud or coral, and some even locate a suitable nest. NOAA gives the example of the Pacific sand lance, which burrows into sand to rest, conserve energy and avoid predators. The agency adds that the nature of fish sleep is an area of active research, so the picture may change.