Can Oura Ring Blood Oxygen Saturation Sensing (SPO2) Detect Sleep Apnea?
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1. What breathing-related metrics does the Oura ring track?
1.1. Respiratory rate
The respiratory rate tells you how many breaths per minute you take. Oura ring counts the respiratory rate using the heart rate measurement. Oura respiratory rate is an average respiratory rate for the entire night. The respiratory rate does not give any indications of breathing disturbances.
Depending on the source, the normal respiratory rate for an adult is between 12-16 or 12-20 breaths per minute.
1.2. Average blood oxygen saturation (SPo2).
All cells in the body need oxygen. When you inhale, oxygen molecules pass through the lungs into the bloodstream. Oxygen saturation (spO2) describes the amount of oxygen in the blood.
Wikipedia gives a more precise definition for blood oxygen saturation. "Oxygen saturation measures the percentage of hemoglobin binding sites in the bloodstream occupied by oxygen."
If you are not breathing, oxygen molecules cannot pass through the lungs into the bloodstream, and blood oxygen saturation drops.
Less than 95-90% oxygen saturation is generally considered low. But it is important to note that medical professionals usually measure a single snapshot of blood oxygen saturation during the day with a pulse oximeter or a blood test.
Oura and other wearable devices track blood oxygen saturation continuously while you sleep and calculate the average for the whole night. Currently, there are no standard values for average night-time oxygen saturation values.
1.3. Ōura breathing regularity/blood oxygen variation.
Ōura breathing regularity shows the variation of blood oxygen saturation during the night.
Frequent variations in breathing regularity can signal breathing disturbances or a problem in how lungs use oxygen; oxygen does not pass through the lungs into the bloodstream.
The blood oxygen variation is optimal if no breathing interruptions occur during sleep. In this case, the variation of blood oxygen is minimal.
When there is a noticeable breathing disturbance, the blood oxygen saturation decreases accordingly. In this case, the blood oxygen saturation variation is greater, possibly indicating breathing interruptions during sleep.
Ōura gives the following estimates of oxygen saturation variation.
- Optimal: no significant variations to display
- Good: few variations detected (dark blue line)
- Fair: occasional variations detected (light blue line)
- Pay attention: frequent variations detected (white line)
Each line on the breathing regularity timeline reflects 15 minutes of sleep.
2. How accurate is Oura ring blood oxygen saturation sensing?
Currently, Oura ring's blood oxygen saturation sensing accuracy is not been externally validated.
According to Oura, a scientific validation study is undergoing; we eagerly await results.
3. How does the Ōura ring measure SPo2?
The infrared and red LEDs in the Ōura ring transmit light to the finger, and the sensors measure how much light is reflected.
Blood with a lot of oxygen is red, reflecting more red light than infrared. Blood with less oxygen is bluish red and reflects more infrared light than red light. Based on these signals, Ōura estimates the blood oxygen saturation in the blood.
Oura SpO2 blog post goes more into detail about Sp02 tracking.
3.1. How often does Oura measure blood oxygen levels?
You can see the red LED light under your Oura ring when it tracks blood oxygen saturation. Usually, the LED light is on all night as Oura measures SpO2 thought the night.
Oura app analyzes the blood oxygen saturation data only when you connect the ring to the Oura application on the phone.
Oura app displays the blood oxygen saturation reading for one sleep period per day that lasts more than three hours. This means Oura does not show the blood oxygen saturation readings from naps.
Each line on the breathing regularity timeline reflects 15 minutes of sleep.
Based on how Oura presents the data in the application, some might think Oura measures blood oxygen saturation every 15 minutes. This is not true.
3.2. Can Oura ring alarm you if the SPo2 level is low?
Ōura's representative commented in a Reddit discussion that the app doesn't analyze blood oxygen saturation data in real-time, so Oura can't issue warnings about low oxygen saturation levels.
Ōura analyzes blood oxygen saturation after waking up when the ring is connected to the application.
4. Can Oura ring detect obstructive sleep apnea (OSA)
The Oura ring is not qualified for the medical diagnosis of sleep apnea, and the FDA has not approved the Oura ring for this purpose.
However, the Oura ring identifies suspected breathing interruptions during sleep. However, these are only suspected disturbances in breathing regularity as Oura is not either approved to detect breathing disturbances or SpO2.
It is also essential to notice, that not all breathing interruptions indicate sleep apnea.
Only doctors can diagnose sleep apnea. In many cases, doctors use a proper sleep study with FDA-approved devices to make the diagnosis.
4.1. What if Ōura warns: Pay attention - frequent variations detected?
It is a good idea to ensure that the ring is firmly on the finger and that the ring's sensors are facing downwards. The blood oxygen saturation sensing may show incorrect results if the ring is not snugly on the finger, as movement makes the measurement harder.
Instead of looking at the breathing regularity of one night, it is a good idea to look for longer-term trends and see if frequent variations occur often.
The word apnea means cessation of breathing. Interruptions in breathing can reduce sleep quality. Frequent variations may be a good reason to pay closer attention to sleep and maybe talk to a medical professional, especially if one is often tired during the day.
Snoring can also be related to sleep apnea, but this is not necessarily the case. Sleep apnoea can also occur without snoring.
There are applications in the app stores that can detect snoring at night. These applications measure the duration of snoring and record what your snoring sounds like.
Everyone has to judge whether it is worth talking to a doctor about the breathing-related issues identified by the Ōura ring. Neither the Ōura app nor online articles can answer the question for you.
4.2. Tiredness - obstructive sleep apnea (OSA) questionnaires
You might be able to evaluate tiredness with the help of two sleep apnea questionnaires, but only a doctor can make a diagnosis. Self-made tests are not sufficient.
Obstructive sleep apnoea (OSA) questionnaires:
Some Oura users might get concerned and anxious about the Oura app breathing regularity messages, but this might be a good wake-up call to take action.
4.3. Two examples of how wearable devices have helped users to get diagnoses for sleep apnea.
Fitbit has been able to track blood oxygen saturation since 2020. There are several comments on Reddit where Fitbit's oxygen saturation measurement has indicated breathing interruptions, and after visiting the doctor, the user has been diagnosed with sleep apnea.
Again, it is good to note that frequent or large variations don't automatically indicate sleep apnea, but those are something you definitely want to research further.
Fitbit and Ōura show variations in blood oxygen saturation, but these two devices visualize the variations differently. Currently, Ōura doesn't provide a graph of the variations.
Two Fitbit sleep apnea examples:
4.4. How is sleep apnea treated?
If the sleep apnea is mild, the doctor may recommend losing weight, quitting smoking, switching from sleeping on the back to sleeping on the side, or treating a stuffy nose.
In more severe cases of sleep apnea, the doctor may recommend a CPAP device or other medical interventions.
5. Blood oxygen saturation in the Oura app.
5.1. What to do if the Ōura app doesn't show blood oxygen saturation (SPo2) values?
If Ōura does not report blood oxygen saturation or breathing regularity, ensure the feature is turned on from the Ōura menu.
Ensure the ring is snugly on the finger, with the sensors facing down. Also, check that the ring is not in airplane mode and Bluetooth is on.
You can find the oxygen saturation and sleep regularity values in the Sleep view in the Ōura application.
5.2. How to find the blood oxygen monitoring in the Oura app?
You can find oxygen saturation under the sleep stages view in the sleep tab.
5.3. Does Ōura show a continuous graph of the SPO2 for the whole night?
No. At the time of blood oxygen saturation sensing release, Ōura does not show oxygen saturation as a graph for the whole night, unlike many other wearable devices.
Ōura has commented that it is exploring the possibility of showing a continuous SpO2 graph in the future.
If you want to see this feature in the Ōura ring, it might be a good idea to contact Ōura and let them know.
5.4. Does Oura SpO2 sensing work on Android?
Oura SpO2 tracking feature is available in both Android and iPhone apps.
5.5. Can Ōura ring sync blood oxygen saturation measurements to Apple Health?
In the summer of 2022, the Ōura app cannot sync blood oxygen saturation measurements to Apple Health.
Ōura has commented they might add this feature later.
5.6. Does the oxygen saturation measurement affect Oura's sleep or readiness score?
The blood oxygen saturation measurement does not affect Oura's sleep or readiness score.
However, Oura may give you advice on the front page based on blood oxygen saturation in case it detects something abnormal.
6. Do I need an Ōura monthly paid membership to track blood oxygen saturation?
Yes. You cannot see blood oxygen saturation (sp02) or breathing regularity measurements without Ōura's paid monthly subscription (price ranging from $5,99 to $6,99).
Without a paid membership, the Ōura app only shows three Ōura scores: readiness, sleep quality, and activity. Membership is required to see more specific scores, measurements, and advice.
All Ōura buyers receive a complimentary six-month Ōura subscription with all Ōura ring features.
7. Can the old Oura Gen 2 ring measure oxygen saturation?
No. Only the newer Gen 3 ring, released at the end of 2021, measures blood oxygen saturation.
8. On which finger should I wear the Ōura ring?
Ōura recommends that you wear the ring on the index finger of the non-dominant hand. The middle finger is the second best option.
Whichever finger you use, the ring must fit snugly on the finger.
9. Does Oura's SpO2 measurement consume more battery?
Oura says that blood oxygen saturation sensing reduces the ring's battery life by about one day per charging cycle.
Before the release of SpO2 tracking, Oura has said that the battery of the generation 3 ring lasts for 4-7 days.
Based on this information, Oura's battery will probably last 3-6 days if you use blood oxygen saturation sensing every night.
Several Oura users have commented that t hey must charge the ring much more than what Oura estimates if they use oxygen saturation sensing. We don't know yet why this is the case.
You can turn off the Oxygen saturation sensing in the Oura application.
9.1. How to turn off Ōura blood oxygen sensing?
You can turn off the blood oxygen saturation sensing from the Ōura app menu by selecting the "Breathing regularity" item and switching off the "Blood Oxygen sensing." As a default, blood oxygen sensing is turned on.
If you disable the feature, you can see your previous oxygen saturation measurements in the Ōura application, but Ōura does not take new measurements.
Turning off the blood oxygen saturation function does not affect sleep or readiness scores.
10. Does altitude affect the blood oxygen saturation measurements?
Blood oxygen saturation is naturally lower in higher altitudes compared to sea level.
A person living at an altitude of 3400 meters can have lower than average blood oxygen saturation. The oxygen saturation increases when this person spends a holiday at lower altitudes. The following Reddit post shows an interesting example.