Blood Oxygen feature returns on Apple Watch - what this could mean for future health metrics.

Apple Newsroom:

Apple will introduce a redesigned Blood Oxygen feature for some Apple Watch Series 9, Series 10, and Apple Watch Ultra 2 users through an iPhone and Apple Watch software update coming later today.

Users with these models in the U.S. who currently do not have the Blood Oxygen feature will have access to the redesigned Blood Oxygen feature by updating their paired iPhone to iOS 18.6.1 and their Apple Watch to watchOS 11.6.1. Following this update, sensor data from the Blood Oxygen app on Apple Watch will be measured and calculated on the paired iPhone, and results can be viewed in the Respiratory section of the Health app. This update was enabled by a recent U.S. Customs ruling.

There will be no impact to Apple Watch units previously purchased that include the original Blood Oxygen feature, nor to Apple Watch units purchased outside of the U.S.

You won’t get measurements directly on your watch; you will have to go to your iPhone’s Health app to view the data. Still better than nothing, but it begs the question:

Is this a precursor to improved health features in the near future?

For one, sleep apnea detection could be more accurate with this new information. From a post I wrote back in January:

If you look at Apple’s study, sensitivity for severe sleep apnea had a sensitivity of 89.1%, while sensitivity for moderate sleep apnea was 43.4%, giving an average score of 66.3%. What that actually means is the Apple Watch is best at detecting severe sleep apnea 89% of the time. It is not that great at determining moderate sleep apnea at only 43%.

Apple would rather underdiagnose people than give false positives, which is still better than no diagnosis at all. They were able to get this far with just the accelerometer sensor:

“The Sleep Apnea Notification Feature is a software-based medical device that analyzes Breathing Disturbance data collected nightly by the Apple Watch accelerometer sensor.”

I wonder how much better the Apple Watch could have been at detecting Sleep Apnea if they included Blood Oxygen data, which is another key component in diagnosing sleep apnea. To perform another study at this scale would take years, but it wouldn’t surprise me if Apple’s sleep apnea detection gets better sensitivity with more crucial data points like blood oxygen levels once the battle with Masimo ends.

Who knows, maybe Apple has two sets of data when they did the study, one with just the accelerometer and one with both the accelerometer and blood oxygen sensor.