Fitbit's Ionic smartwatch was the brand's first product to feature an SpO2 sensor, which is used in estimating blood oxygen levels. Several other Fitbit products, namely the Versa, Versa Lite, Versa 2, and Charge 3, came with a similar sensor, but it had stayed dormant until December. After being tested with a few users, the feature appears to be rolling out more widely.
Fitbit recently added an "Estimated Oxygen Variation" graph to sleep data in its app, showing important oxygen saturation variations while you're snoozing, but not throughout the rest of the day. The company had previously recognized that this graph was rolling out to a "small percentage of users," but an increasing number of people have recently reported that it showed up for them.
While Fitbit hasn't officially confirmed whether the functionality is now widely available, it has indicated it's developing "FDA-cleared features for sleep apnea," which means the SpO2 sensor will probably be used for more detailed analytics. That comes at a time when several other activity tracker companies have started offering similar capabilities. Withings, one of Fitbit's biggest rivals, recently unveiled the ScanWatch, which features both AFib and sleep apnea detection.
Wider roll out
After the initial rollout in January, more and more users are now reporting seeing the blood oxygen saturation graph in the Fitbit app. We've seen confirmations from the US, UK, and Canada, but it's possible this isn't geo-restricted but a simple slow server-side rollout. Keep in mind you need to have a compatible Fitbit tracker to get the functionality, so this won't be available to everyone.