Every night, your brain and body experience different phases of sleep, and each one plays an essential role in maintaining your mental and physical health. Use the Oura App to track the quantity and quality of your night's rest, take note of your high points, and identify areas that might need your attention.
What Are Sleep Stages?
Sleep stage data measured by Oura are available in the Sleep tab of the Oura App, and are displayed in color-coded sleep stage graphs called "hypnograms."
The Oura Ring measures four separate stages of sleep:
- Awake: the time you spent in bed before and after falling asleep. This also includes brief awakenings that occur during sleep
- REM: rapid-eye-movement (REM) sleep involves increased brain activity and is often associated with vivid dreaming
- Light: light sleep guides you into deeper stages, and acts as the beginning of or transition between each sleep cycle
- Deep: also known as slow-wave sleep, deep sleep is when your body repairs and restores itself
Every individual's sleep requirements are different, though the recommended amount is 7-9 hours for most adults. This is enough time for your body to go through four to five 90-minute sleep cycles. In general, you spend most of the night in light sleep.
You can find more information on our blog: What Are the 4 Stages of Sleep?
How Sleep Stages Are Measured
Oura uses data from many of your biosignals — including movement, skin temperature, resting heart rate, heart rate variability (HRV), and respiratory rate — to determine which sleep stage your body is in. Here are some of the indicators that Oura looks for at each stage:
- Respiratory rate slows
- Heart rate decreases
- Body temperature drops
- Low movement
- Heart rate and respiration stabilize
- Skin temperature is at its highest
- Respiratory rate increases
- Heart rate increases
Learn more about Oura's sleep measurement on our blog: How Does the Oura Ring Track My Sleep?
New Sleep Staging Algorithm
In May 2023, Oura began rolling out a new sleep staging algorithm for the Oura Ring Gen3. This new algorithm was developed to take advantage of the Gen3 ring's extra sensors and increased memory capacity in order to provide even more refined sleep stage detection.
Using one of the largest sleep datasets-to-date, collected over hundreds of participants across three different continents, Oura's new sleep staging algorithm achieves 79% agreement with polysomnography (PSG) sleep lab tests.
The increased accuracy of the new sleep staging algorithm does not mean that the data from the previous algorithm was incorrect. Independent validation studies have demonstrated that Oura’s previous sleep staging algorithm still performed similarly to —or better than — most other consumer wearables.
Find more information about these validation studies and the accuracy of our sleep algorithms on our blog: Oura’s New Sleep Staging Algorithm: More Accurate Than Ever Before
Changes to Your Oura Data
For Oura members with Gen3 rings, the release of the new sleep staging algorithm includes several changes to the Oura App.
- If you were part of our sleep staging beta, you will no longer see the toggle to switch between the previous algorithm and the new sleep staging algorithm
- There will be a tag in your Trends that marks the day when your data switched over from the previous algorithm to the new sleep staging algorithm
Some Oura members with Gen3 rings may see changes to their data. With the added sensitivity of the new algorithm, it’s perfectly normal to see a different ratio of your sleep stages, especially an increase in light sleep. For most healthy individuals, light sleep accounts for >50% of a typical night of sleep and can account for up to 60% in older individuals.
While a lot of factors determine the magnitude of changes you’ll see in your data, HRV has a large impact depending on whether you have higher, average, or lower HRV.
- Members with higher HRV may see a large decrease in Deep, large increase in Light, small increase in REM, and little or no change in awake
- Members with average HRV may see a large decrease in Deep, large increase in Light, small decrease in REM, and little or no change in awake
- Members with lower HRV may see a large decrease in REM, large increase in Light, small decrease in Deep, and small increase in awake
Learn more about the heart rate variability (HRV) measurements taken by the Oura Ring here.
Sleep stages play an important factor in your "Previous night" and "Sleep balance" contributors, so the new sleep staging algorithm may temporarily impact your Readiness and Sleep Scores. Changes to your scores will be most noticeable up to two weeks after the launch of the new algorithm, and will stabilize over the following two months as Oura recalibrates your baselines. Around 1% of Gen3 users may see a 7-9 point drop in their scores during this period, though for a majority of Oura members the changes will be less sizable.
Gen2 rings will continue to use the previous sleep staging algorithm and will not have any data changes. Both algorithms uphold high accuracy standards that Oura has set for itself and continue to provide a comprehensive view of trends in your sleep over time. The new algorithm will not have any impact on any of your data recorded prior to the changeover.