Sperm whales sleep in a unique way compared to other mammals. Unlike humans, they don’t sleep continuously but instead enter short, deep sleep cycles. These whales are known to sleep vertically, slowly drifting in the water with their heads pointing downward. During these periods, they remain partially conscious, allowing them to surface for air and avoid predators. Sperm whales sleep for around 7-8 hours a day, often in shallow waters. Their brains also exhibit unihemispheric slow-wave sleep, where one hemisphere rests while the other remains active, allowing them to maintain basic bodily functions and awareness of their surroundings.