27. Manatees
Manatees are gentle giants with a peaceful approach to sleep. They rest while fully submerged, surfacing for air every few minutes thanks to their slow, steady metabolism.
Unlike many land mammals, manatees’ aquatic environment shapes their unique sleep cycles, allowing them to doze while drifting or lying on the riverbed. This tranquil way of sleeping helps them conserve energy and remain safe in their watery habitats. USGS