This is kind of a typical NPR headline. They're not _really_ saying that the lost art of breathing impacts sleep and stress. What they really mean is: There's this guy who _says_ that there is a lost art of breathing and we're gonna tell you what he thinks.
BJJ and a Wim Hof demonstration have taught me a lot about stress management and breathing. I do some of the exercises daily like hot to cold shower (wakes up the parasympathetic response). Interesting topic - a bit of a gloss by NPR though