[mountain_peak]

Your thoughtful question is definitely along the lines where the research could change health outcomes. Apple Health currently tracks trends over time and can alert if any disconcerting trends are identified. If Apple were able to capture a breathing signature at rest, say once a month, trends could be identified (via training data, as you mention) and data optionally provided to healthcare providers.

Some people who are alone (including my father) have no idea that they have sleep apnea or 'odd' breathing - for apnea, they're obviously asleep, and for other breathing factors, it's usually a slow and unnoticeable progression.