That's interesting. Does anyone have a good journal reference for the following assertion made in the piece? "A physiological sigh, two or three times, is the fastest way that we are aware of to bring the level of autonomic arousal back down to baseline." I would like to know what the evidence is for that. The interviewee made it sound like reinflating alveoli and offloading carbon dioxide necessarily leads to a decrease in autonomic arousal, but I don't see why that would necessarily be the case. If the mechanism is instead related to the movement of the diaphragm, as is hinted at later in the piece, I would be interested in seeing strong evidence for that, too.