SpO2 (blood oxygen levels) is actually very useful if it's accurate. (Apple's implementation is not super accurate because SpO2 measurement from the wrist is f

SpO2 (blood oxygen levels) is actually very useful if it's accurate. (Apple's implementation is not super accurate because SpO2 measurement from the wrist is fraught to start with -- it's usually measured from the finger -- and it is biased by skin colors etc.). Prolonged low blood oxygen means insufficient oxygen is being carried to organs and tissues. Apart from sleep apnea, it can make pre-existing conditions worse. My ophthalmologist tells me that chronically low blood oxygen can cause problems to organs like the retina which is sensitive to oxygen deprivation.