Researchers observing marine mammals in far northern seas are seen releasing controlled streams of bubbles to help stay afloat during short rest periods upright in the water.
A team attached tracking tags to whales as part of efforts to study natural sleep behavior in their usual habitat.
The work hints that the oversized melon-shaped organs do not really cause tipping or wobble while at rest.
Several of the cows have been seen floating with their bellies up in the water column to hold onto calories.
The position could offer support to nursing mothers while away from the group, members of the team point out.
That noted adjustment may expand461 research on animal rest, researchers write.