Smart watches have emerged in recent years as useful tools for, among other things, tracking health data and sleep in particular. Most smartwatches on the market claim to be able to track sleep stages and quality of sleep, while others also track blood oxygen saturation which is used to detect likely sleep apnoea. But how accurate are these devices? Can your watch diagnose you with sleep apnoea and save you having to do a sleep study?
Diagnosing Sleep Apnoea
To make a formal diagnosis of sleep apnoea, you need to monitor several physiological factors overnight, including:
- Sleep stages (most accurately done with EEG electrodes on head)
- Cardiovascular system
- Oxygen saturation
- Body position
- Respiratory effort
- Airflow
No smart watch or single wearable device is able to definitively diagnose sleep apnoea and it is unlikely they ever will, simply because they lack the ability to directly measure brain and respiratory activity. The only way to truly diagnose sleep apnoea is with a level 1 or 2 sleep study, either in a hospital setting or with a home sleep study, such as provided by Home Sleep.
In 2024, the American Food and Drug Administration (FDA) approved first Samsung’s, then Apple’s, sleep apnoea detection updates in both companies’ smart watches, formally recognising them as medical devices. Similar to a level 4 home sleep test device, such as the ResMed One Test or WatchPAT, these smart watches can monitor cardiovascular, motion and oxygen data and infer the rest using complex algorithms. Even these devices do not directly measure all the required components so are not certified to diagnose sleep apnoea, rather are intended to be used to detect likely sleep apnoea.
Samsung and Apple’s sleep apnoea detection software is intended for people over 22 who have not previously been diagnosed with sleep apnoea. They are designed to help detect signs of moderate to severe obstructive sleep apnoea to encourage users to follow up with a proper sleep study if necessary. It is stated that the devices are not intended for the treatment, symptom observation, tracking or monitoring of sleep apnoea, however there are potential benefits in being able to track the changes in severe sleep apnoea following treatment, with the understanding that there are some limitations in accuracy.
What Do Smart Watches Monitor?
Smart watches that track sleep data measure some combination of movement, heart rate and blood oxygen saturation. This can be a very useful detection tool for severe sleep apnoea, but still not enough to diagnose the issue. If your watch shows significant blood oxygen desaturations overnight, this means you are very likely to have severe sleep apnoea and would be well advised to get a proper sleep study conducted as soon as possible. If your watch shows no oxygen desaturations, however, this does not mean you are necessarily in the clear. Many people with sleep apnoea are woken up frequently by their obstructed breathing, leading to excess stress on their bodies and tiredness during the day but don’t have the associated oxygen losses.
When Should I Get a Sleep Study Done Based on Data from My Watch?
If you have a newer Apple or Samsung watch with the approved sleep apnoea detection software, the app will notify you if sleep apnoea is likely and should be tested further. If you have a slightly less advanced watch, it may still be able to suggest that you are waking up more frequently than you realise, your heart rate is variable, you spend a long time in light sleep or awake when you feel like you’ve slept, or that your oxygen levels are dropping overnight. Any or all of these are signs that you likely have sleep apnoea to some degree and would benefit from getting a proper sleep study conducted to confirm a diagnosis and point you towards the best treatment option for you. Here at Home Sleep, we have seen many patients reach out to us for a sleep study because of data from their smartwatch suggesting likely sleep apnoea and we have been able to diagnose sleep apnoea and quickly get them onto the best treatment to make them feel their best again.
With or without a smartwatch to give you sleep data, if you are excessively tired during the day, wake up with headaches, have poor concentration, have high blood pressure, are a known snorer, ever wake up choking or gasping and/or have been seen to stop breathing at night, it is a good idea to get a sleep study and find out if you are amongst the many millions of people who can easily get healthier sleep and feel better by simply treating their sleep apnoea.
What About Smart Phones?
There are apps available that monitor breathing patterns and snoring through sound and movement through the phone’s accelerometer which requires you to have your phone in the bed with you. These don’t look at heart rate or oximetry so are even less accurate than watches at measuring sleep stages, but through sound and movement can be useful indicators of likely sleep apnoea. If your sleep app suggests likely sleep apnoea, whether through loud snoring or if it’s detected you waking up frequently, it’s a good idea to follow up with a level 1 or 2 sleep study to get a definitive diagnosis.