Obstructive sleep apnea is one of the most common sleep disorders and one of the most often missed. Many people who have it never get tested, because the classic warning signs (loud snoring, gasping awake, feeling wrecked by mid-afternoon) are easy to shrug off. Smartwatch makers have been pitching a fix: let the device you already wear to bed watch for the problem. This month brought two pieces of news on that front: a Stanford study testing how well one watch actually does the job, and Apple's rollout of a similar feature in China.
What the Stanford team tested
The study, published in late August in the Journal of Clinical Sleep Medicine and publicized by the American Academy of Sleep Medicine in mid-October, looked at the sleep apnea feature on the Samsung Galaxy Watch 6. Dr. Robson Capasso, a professor of otolaryngology–head and neck surgery at Stanford University, was the principal investigator. Arash Alavi, director of software engineering at Stanford's Deep Data Research Center, was lead author.
The researchers enrolled 147 adults with an average age of 54. Every participant either already had a moderate-to-severe sleep apnea diagnosis or was considered highly likely to have one. Each wore the watch for two nights of in-lab sleep testing at the Stanford Health Care Sleep Medicine Center and three nights at home. The team then checked the watch's verdicts against overnight sleep studies, the standard way sleep apnea is diagnosed.
What they found
- It caught most people who had the condition. At its default setting, the watch had 94% sensitivity for moderate-to-severe sleep apnea, meaning it flagged about 94 of every 100 people who truly had it.
- It also flagged plenty of people who didn't. Specificity was 67%. Roughly one in three people without moderate-to-severe apnea would still get a warning.
- It was strongest for the riskiest cases. In people with a high "hypoxic burden," a measure of how deeply and for how long blood oxygen drops during breathing pauses, the watch was 100% sensitive and 100% specific in this sample.
The researchers were explicit about what the watch is for. Capasso said the devices are not diagnostic, and the team framed the result as support for using consumer wearables to screen, meaning flag people who should go on to get a proper sleep test.
How to read those numbers
A screening tool that catches nearly everyone but over-flags is a deliberate trade-off. Missing a case of serious sleep apnea carries real costs, because untreated moderate-to-severe apnea is tied to high blood pressure, heart disease, and drowsy driving. A false alarm, on the other hand, usually costs a doctor's visit and a sleep test that comes back reassuring. For a first-pass screen, leaning toward sensitivity makes sense.
Two details matter before applying the figures to yourself, though:
- This group was already high-risk. Everyone enrolled had a diagnosis or strong suspicion of apnea. In the general public, where most people don't have the condition, the same watch would produce a larger share of false alarms relative to true ones. Accuracy in a high-risk clinic sample doesn't carry over neatly to everyday users.
- It only looks for moderate-to-severe apnea. Mild sleep apnea is outside what the feature is designed to detect. No alert doesn't mean no apnea. If you snore loudly, wake gasping, or feel sleepy through the day, talk to a clinician regardless of what your watch says.
It's also worth knowing the study's background. Samsung and Stanford Medicine announced a research collaboration on the watch's sleep apnea feature in April 2025, with Capasso leading it. That doesn't make the results wrong, but the work isn't fully independent of the device's maker, and independent replication in broader populations would strengthen the case.
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Apple's feature expands too
On October 14, Apple brought its own sleep apnea notifications to mainland China after approval from the country's National Medical Products Administration. Apple's version uses the watch's accelerometer to pick up small wrist movements linked to interrupted breathing, reviews the data over 30-day periods, and sends a notification if it sees signs of moderate-to-severe apnea. Users can export a PDF summary to share with a doctor. It runs on the Apple Watch Series 9, Ultra 2, SE 3, and later models.
Samsung's feature was the first of its kind authorized by the U.S. Food and Drug Administration, receiving De Novo authorization in February 2024. In the U.S., it's intended for adults 22 and older who haven't been diagnosed with sleep apnea, and it checks for signs over two nights of monitoring. Apple later received FDA clearance for its own notification feature. Both companies describe these tools as screening aids, not diagnoses.
What to do if your watch flags you
- Take it seriously, but don't panic. A notification means you should get tested, not that you definitely have sleep apnea. As the Stanford numbers show, some alerts will be false alarms.
- Bring the data to your doctor. Note any symptoms you or a bed partner have noticed, such as snoring, breathing pauses, morning headaches, or daytime sleepiness, and share the watch report if your device creates one.
- Expect a real sleep test. Diagnosis typically comes from an in-lab sleep study or a prescribed home sleep apnea test, which measures breathing and oxygen levels directly.
- Know that treatment works. If you're diagnosed, options range from CPAP therapy to oral appliances and, for some people, lifestyle changes like weight loss and side sleeping.
Key takeaways
- A Stanford study of 147 high-risk adults found the Samsung Galaxy Watch 6 flagged moderate-to-severe sleep apnea with 94% sensitivity and 67% specificity at its default setting.
- It caught every case among people with high hypoxic burden, the group with the most severe oxygen drops.
- The watch is a screening tool, not a diagnosis. Expect some false alarms, and don't treat a lack of alerts as an all-clear, especially for mild apnea.
- Apple expanded its sleep apnea notifications to mainland China on October 14, putting this kind of screening on more wrists.
- If you get flagged or have symptoms, the next step is a proper sleep study.
The bigger story is that sleep apnea screening is moving out of the clinic and onto the wrist. That could help reach millions of people who would never book a sleep study on their own. The watch only gets you to the door, though. Diagnosis and treatment still go through a clinician and a real sleep test.
Source: News-Medical (news release from the American Academy of Sleep Medicine) — "Consumer smartwatch helps identify adults with severe sleep apnea," October 13, 2026, https://www.news-medical.net/news/20261013/Consumer-smartwatch-helps-identify-adults-with-severe-sleep-apnea.aspx. Study: Alavi A., Capasso R. et al., "Smartwatch-based detection of moderate-to-severe and high-risk obstructive sleep apnea," Journal of Clinical Sleep Medicine, doi:10.1007/s44470-026-00159-8. Additional context: MacRumors, "Apple Watch Sleep Apnea Notifications Launch in China," October 14, 2026, https://www.macrumors.com/2026/10/14/apple-watch-sleep-apnea-notifications-china.
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Consumer smartwatches cannot diagnose sleep apnea. If you have symptoms such as loud snoring, breathing pauses during sleep, or excessive daytime sleepiness, talk to a qualified healthcare provider about a sleep evaluation.
About Better Night Sleep: Better Night Sleep is an independent sleep-education and product-research resource. Our articles are written and edited by the Better Night Sleep editorial team using reputable public sources and established sleep-health recommendations. Learn more about us.