Sleep is having a moment. We’ve recently seen prominent documentaries released on sleep, the emergence of sleep influencers on social media platforms, and even sleep tourism! Yes, it’s a thing.

A strong driver of this increased interest is the emergence of smart devices that let people track their sleep. These devices are giving many of us new perspectives on our sleep, and at a granular level – breaking down our night’s sleep into easy to visualise categories and scores.

Armed with this information, people can use these devices to tune their sleep cycles just as they would use them to tweak their diet, their exercise routine, or their minute-to-minute activity levels. Far more than just helping people count how many hours of REM sleep they’re getting, these technologies are also shining a light on one of the world’s most prevalent sleep disorders: sleep apnoea.

A night-time companion for millions of Australians

Sleep apnoea involves interruptions in breathing during sleep. These interruptions can last from a few seconds to minutes and can occur multiple times throughout the night. The most common type is obstructive sleep apnoea (OSA), caused by a blockage of the airway, usually when the soft tissue in the throat closes during sleep. Affecting up to 38% of the population by some counts[1], OSA impacts millions of Australians and over a billion people worldwide, with a commensurate impact on our healthcare system.

Common symptoms during sleep include snoring, gasping for air, and low blood oxygen levels. Upon waking, these interruptions in sleep leave affected people under-rested, resulting in excessive daytime sleepiness and difficulty concentrating. It can also lead to health problems including cardiovascular issues, high blood pressure, and diabetes. In patients with these comorbidities, health professionals often fail to detect the underlying sleep apnoea – just one reason why approximately 80% of people with OSA remain undiagnosed and untreated.

A new era in OSA detection

These same devices that are slicing and dicing your night’s sleep into REM, light, and deep sleep and spitting out a score are now offering to help detect signs of sleep apnoea.

In the past, simple phone-based apps would use the onboard microphone to detect a person snoring, correlating that to a risk of apnoea. Newly launched features on Apple and Samsung smartwatches are taking a different approach, measuring wearer movements during the night using onboard accelerometers to detect breathing disruptions. In addition, Samsung Galaxy Watches use their onboard pulse oximeters to measure blood oxygenation levels.

To form a recommendation, the watch must be worn for a set period of time – two consecutive nights for Samsung Galaxy Watches, and at least 10 nights within a 30-day period for Apple Watches. This data is then processed by a proprietary machine learning algorithm, that calculates whether the wearer is at an elevated risk of sleep apnoea – both manufacturers are careful to note that any recommendations from the watch require confirmation by a doctor.

Sleep apnoea by the numbers

Both algorithms were assessed against the gold standard of polysomnography (PSG) in a sleep laboratory and both achieved clearance from the U.S. Food and Drug Administration (FDA) as “safe and effective” to “assess risk of sleep [apnoea]”.

But how accurate are these systems? And how many people will they help? To answer these questions, we sifted through both companies’ published data as well as a range of third-party sources.