Do whales sleep Whales have developed several exciting strategies for sleeping in their underwater environment. They can sleep while floating near the surface, resting quietly in the water, or swimming slowly alongside other whales. Due to their need for regular breathing, whales cannot afford to sleep deeply for extended periods. Instead, they use unihemispheric slow-wave sleep (USWS) to keep half of their brain active while the other half rests. This method allows them to stay alert to predators and environmental changes. https://litefacts.com/do-whales-sleep/