Breathing Innervation Question

I've been told by meditation & yoga instructors and naturopathic doctors that inhalation is controlled by sympathetic innervation, and exhalation is parasympathetic. Based in this, we are taught to change our meditation breathing based on whether we desire to emphasize activation or calming. The idea is that by extending the inhale and shortening the exhale, you increase your sympathetic activity. More often the idea of extending the exhale to double or more the length of the inhale is used, to help us release the stresses of modern life.
( a question )