Whales Sleep Vertically: new tags reveal sperm whale bubble rests; study probes gas exchange

Scientists from the University of St Andrews and Université de Neuchâtel tagged sperm whales off Norway and found they release gas bubbles while sleeping vertically to remain suspended below the ocean surface.

Sperm whales are the only known whale species that routinely sleep in a vertical position, often with heads pointing to the surface and bodies trailing down.

The vertical sleeping position helps whales breathe easily when they wake, protects from ocean wave motion, and avoids energy loss from drifting into deeper waters.

The sperm whale's head contains a spermaceti oil organ that makes it naturally positively buoyant, so releasing gas bubbles helps regulate buoyancy to stay suspended.