User level: Level 1 (12 points)Upgraded to the Series 12 recently and my blood oxygen readings dropped to 93%–95.5% during sleep.
On my Series 11, It was consistent between 96%–99%.
I feel completely fine, no shortness of breath or fatigue. The fit is snug and sitting above the wrist bone (non-US model, so SpO2 is active).
Is the new sensor is more accurate due to hardware or algorithm change?
Anyone else seeing this?
Posted on Sep 28, 2026 3:29 PM
User level: Level 8 (43,363 points)Sep 28, 2026 4:00 PM in response to GauravSingh02
If you really think this is a serious issue, visit your Doctor and get a blood O2 test, which will be more accurate than either watch, and certainly more informative than random idiots on Reddit.
Both watches are using indirect measurements, and frankly as long as as your readings are above 90%, you don’t really have an issue. Just a small variance of the fit of each watch could have an impact. If you have other symptoms, see your doctor.
You ca also give Apple feedback here, but without something more concrete, your not giving them anything to fix: Product Feedback - Apple
User level: Level 1 (12 points)Sep 28, 2026 3:46 PM in response to Kilgore-Trout
No, its not based on just 1 day record. Every single day, the SpO2 reading came low on series 12.
and if you visit the Reddit post link I provided, you can read i am not the only one experiencing this.
its an issue from Apple , I hope they fix it soon
User level: Level 8 (43,363 points)Sep 28, 2026 3:37 PM in response to GauravSingh02
Based on your post, it would appear you are basing this on one night’s reading? No where near enough data to draw any conclusion. The sensors on the newer may be more accurate on this measure, or not.
Originally posted at discussions.apple.com/thread/256366801