When I was diagnosed with sleep apnea, it wasn't the breaths per hour that was the concern, it wasn't waking up during the night, it was my blood oxygen would d

When I was diagnosed with sleep apnea, it wasn't the breaths per hour that was the concern, it wasn't waking up during the night, it was my blood oxygen would dip to the 60s. So the researcher measured heart rate, breathing rate and not blood oxygen? Or maybe they did, and the headline of, "People hold their breath sometimes, blood oxygen remains in normal ranges", doesn't inspire me to learn how to breath.