Research teams studying whales near polar waters are seen releasing puffs of air to help control their position in the water during short rest periods in a vertical stance.
Tagged animals included nearly four dozen animals to record natural sleep behavior without disturbance.
New findings suggest the oversized melon-shaped organs do not really cause tipping or wobble while at rest.
Several of the cows appear to rest inverted in the water column as a recovery method to hold onto calories.
That posture may assist cows feeding calves in the gaps between meals, researchers say.
That documented habit help broaden the limited record of how giants of the deep pause for hours at a time, researchers write.