Scientists report that sperm whales can sleep while floating in a distinctive vertical position just below the ocean surface by releasing gas bubbles. The findings, published from research involving the University of St Andrews and Université de Neuchâtel, describe how the whales control their buoyancy during rest. By adjusting the release of gas bubbles, the whales are able to stay suspended with minimal movement, allowing them to remain motionless while resting in the water column. The research focuses on the mechanism behind the animals’ long-observed “vertical sleeping” behavior, where they hang head down near the surface rather than drifting horizontally like many other marine mammals. Multiple outlets summarize that the bubble release regulates buoyancy, keeping the whales at a stable depth during sleep. The reports present the study as identifying how the whales achieve a restful posture while reducing the need for active swimming. Overall, the sources agree that gas bubbles play a key role in the whales’ ability to maintain vertical, near-surface sleep.