An Introduction to Respiratory Rate
Interested in learning more about your respiratory rate in Oura? In this article, we’ll cover how Oura measures this metric, offer suggestions for how to interpret changes in your respiratory rate, and discuss the accuracy of our approach.
How Oura Measures Respiratory Rate
The respiratory rate displayed in your Oura App shows how many breaths you took per minute during the previous night, on average. This value can be found in your Readiness tab, as well as in Trends .
Oura estimates respiratory rate at rest via minute-by-minute changes in your nighttime heart rate. This calculation is possible because your heart and lungs are closely connected by a process called respiratory sinus arrhythmia. This relationship reveals the following:
- When you breathe in, your heart rate increases.
- When you breathe out, your heart rate slows down.
Because Oura is able to accurately measure the pulse waveform produced by each of your heartbeats using the PPG sensors located inside your ring, it can also correctly measure the distance between consecutive heartbeats in milliseconds. This distance is otherwise known as the interbeat interval (IBI). If you’re familiar with heart rate variability (HRV), IBIs are the building blocks of HRV.
By mapping out IBI values over the course of a night, an “up and down” pattern will gradually form—check out the image below for a visualization of this.
In direct opposition to the respiratory sinus arrhythmia relationship described earlier, when you observe IBI values decreasing, this signals that you’re breathing in. When you observe IBI values increasing, this signals that you’re breathing out. Each increase and decrease that occur together in the visual map of IBI values equates to one breath (these visually appear as “spikes,” similar to mountain-like peaks). Since each “spike” in the map represents one breath, by measuring the number of times this pattern occurs each minute throughout the night, your average respiratory rate can be determined.
Interpret Your Respiratory Rate
An average respiratory rate for healthy adults is 12–20 breaths per minute. Changes in your average respiratory rate tend to be quite small from night to night (within 1–2 breaths per minute). This is because the amount of oxygen you need at rest is likely to remain constant, making respiratory rate a very stable metric. A deviation in your respiratory rate greater than two breaths per minute from your average (as demonstrated in the example below), is a sign worth paying attention to.
It’s essential to note that respiratory rate is individual to you, meaning you should only compare changes relative to your own baseline and not with other people’s data. Knowing your average respiratory rate, as well as your typical fluctuations within Oura, can help you stay attuned to when a change is outside your normal values.
If your respiration rate is elevated from your baseline, it may be a sign that your body is under strain.
Consider these as potential causes for a rise in respiratory rate:
- Fighting Off Illness: Respiratory rate is likely to increase with elevations in resting heart rate and decreases in heart rate variability when you’re falling ill. In the case that you're battling off a respiratory tract infection (e.g., bronchitis), increases in respiratory rate have to do with short-term damage done inside the lungs. Because these types of infections often impact the cells where gas exchange occurs between the air and your lungs, the oxygen and CO2 exchange process will naturally become less efficient under these circumstances. This leads to an elevated respiratory rate to make up for the difference.
- Air Quality or Altitude: Lower air quality will likely require your body to work harder to deliver the same amount of oxygen to your system that’s necessary for survival. This is because each breath is not gathering the same amount of oxygen it normally would in an environment with higher air quality, resulting in more breaths per minute to sustain your system. Similarly, because the oxygen content of air at higher altitudes is lower, your respiratory rate will naturally rise as you go up in elevation since your body is gathering less oxygen per breath.
- Long-Term Breathing Issues: Heavy snoring, coughing, and excess movement can interfere with the steady rise and fall of interbeat intervals that are used to estimate respiratory rate. This can lead to occasional variation in your data, especially if any of the listed circumstances above apply to you on a more frequent basis.
- Vigorous Exercise: Intense exercise concentrated on muscular endurance or anaerobic fitness (e.g., HIIT training), can cause respiration rate to remain elevated for roughly 20-40 minutes following workout completion. You may want to keep this in mind, especially when considering doing a challenging workout later in the day prior to bed.
- Anxiety: Rapid and irregular breathing patterns are associated with increased anxiety.
- Hormonal Changes: Women tend to have more variation in their respiratory rates, as changes in respiratory rate correlate with stages of the menstrual cycle. Respiration is slower at the beginning of the cycle (follicular phase) and speeds up towards the end (luteal phase).
- Room Temperature While Sleeping: If you’re sleeping in a bedroom that causes you to become hot or cold during the night, you may see changes in your respiratory rate as your body works harder to compensate for these temperature extremes. You’re likely to see slight elevations in your respiratory rate under either condition.
The Accuracy of Oura's Respiratory Rate
In an analysis conducted on behalf of our Data Science Team that compared Oura’s photoplethysmography (PPG)-derived respiratory rate metric to an electrocardiogram (ECG)-derived method, the Oura Ring was shown to be accurate within 1 breath per minute across the entire night.
An electrocardiogram is a test completed in a medical setting that measures the electrical activity of your heart. Because respiration is difficult to measure without invasive tools, ECG-derived respiratory rate is a well-established practice that’s been commonly used and identified as highly reliable in medical-grade research settings.
The results of the study held true across a full range of respiratory rates, from high (>20) to low (<14), observed in the pool of 43 healthy, young adults—classifying the Oura Ring as a valid tool for measuring average nighttime respiratory rate, on par with the ECG-derived method.
You can read more about the study performed with Duke-NUS Medical School and the National University of Singapore here.