Every night, around the world, millions of people go to bed — but their sleep is anything but peaceful. They gasp for air, suffer chronic sleepiness, and face an increased risk of heart disease, hypertension, and Type 2 diabetes. Yet most people who have the condition never receive a diagnosis.
According to Lancet Respiratory Medicine, in 2019, the global burden of obstructive sleep apnoea was estimated at nearly one billion adults, predominantly middle-aged and older adults. The good news is that sleep apnoea is a treatable disorder.
Apple has expanded its sleep apnoea notification feature to Apple Watch users in India. Traditionally, sleep apnoea is detected through polysomnography in a sleep clinic, or via complicated home tests that measure brain activity, heart rate, and movement, among other metrics. Now, all of that data is available from your wrist — simply by wearing your Apple Watch to bed.
The prevalence of moderate to severe sleep apnoea is estimated at approximately 10 per cent of the global adult population, based on a strict scoring convention known as the 4 per cent hypopnoea rule. Research also suggests that up to 80 per cent of cases remain undiagnosed. While some people experience symptoms such as daytime drowsiness or nocturnal gasping, others may have no symptoms at all.
To use the feature, wear your Apple Watch to sleep for a minimum of 10 nights over a 30-day period. Your data is then analysed at the end of each 30-day window.
How does it work? The Watch tracks movement using a triaxial accelerometer, which captures both coarse body motion and finer movements — including those associated with breathing. Apple developed an algorithm that analyses this accelerometer data to identify Breathing Disturbances: temporary interruptions in the breathing pattern during sleep.
The feature has two components — a nightly Breathing Disturbances measurement, and a notification sent to the user if those values remain elevated over a 30-day period, indicating signs of potential moderate to severe sleep apnoea. It is worth noting that neither component is intended for people already diagnosed with the condition.
For frequent travellers, or those crossing time zones regularly, the picture is more nuanced. Dr Rajiv Kumar, clinician-researcher at Apple, explains: "At baseline, any typical user may have a few breathing disturbances overnight — that's not uncommon. And there will be nights when a person is affected more by travel: sleep on a plane, hotel rooms, something different from their usual routine. The feature is set to work within Sleep Focus mode. So even with time zone changes, as long as you are in Sleep Focus (where the Watch anticipates that you are resting), it will look for those disturbances. It examines wide-scale patterns over time. Every 30 days, it looks back at all recorded sleep sessions and asks: are there enough breathing disturbances consistent with sleep apnoea?"
Temporary disruptions such as seasonal allergies or an upper respiratory infection need not skew the results. "The accelerometer detects vibrations of the body as we breathe — it looks for inspiration and expiration," says Dr Kumar. "If someone has a respiratory tract infection or seasonal allergies, it may affect the quality of their breathing, but it shouldn't affect the pauses in respiration that the algorithm is specifically looking for."
As for ageing: whilst sleep patterns do change over time — with less deep sleep, shifts in REM sleep, and shorter overall duration — Dr Kumar is clear that this alone does not directly increase the risk of sleep apnoea. "As we get older, we may have less mobility, more weight, more risk factors for sleep apnoea. But the two aren't necessarily tied specifically to ageing. The algorithm remains specific to that respiratory pattern — those pauses in respiration."
Since sleep apnoea causes repeated nocturnal waking, it can take a significant toll on psychological health. If you receive a sleep apnoea notification, speak to your doctor.
Apple Watch models that support the feature are Apple Watch SE 3, Apple Watch Series 9 (or later) and Apple Watch Ultra 2 (or later).