About sleeping oxygen
For more information about the oxygen sensor and its accuracy, see our main page on Apple Watch’s oxygen sensor.
What’s a good sleeping blood oxygen?
80% of people have an oxygen saturation above 94%. A 90% sleeping blood oxygen is in the bottom 1%, and merits discussion with a doctor. The distinction at levels of 95% or above aren’t necessary medically significant — a 97% vs a 99% blood oxygen saturation is most likely to reflect measurement error than any type of biological reality. The Apple Watch’s blood oxygen sensor isn’t regulated by the FDA (no “over the counter” oxygen sensors are), but the accuracy standard for
Sleeping oxygen vs daytime oxygen
The chart above shows the distribution of sleeping blood oxygen percentiles in Apple Watch users. You can compare your own values to the population using this chart. Most people maintain a sleeping SpO₂ above 90%. Values below this line are less common and may merit further discussion with your doctor.
Interestingly, about 1 in 10 people have daytime oxygen below 95%, compared to 1 in 5 people with sleeping oxygen below 95%. This difference in sleeping vs daytime oxygen can be a sign of underlying sleep apnea.
Low sleeping oxygen and sleep apnea
If your blood oxygen is low during sleep, that can be an indicator of sleep apnea. There are many sources of at-home sleep apnea tests online; some are covered by insurance.
Low sleeping oxygen and COPD
COPD is another common cause of low oxygen saturation. (So is asthma). Your doctor may prescribe you specific medications to take in episodes of COPD exacerbation.
Low oxygen and COVID
A third cause of how oxygen saturation is acute covid infection.
