Smartwatch Sleep Apnea Screening: Stanford Put a Galaxy Watch to Test

Millions of people stop breathing in their sleep without knowing it. Obstructive sleep apnea is one of the most common sleep disorders in the world, and it usually goes undiagnosed until the damage is done. Sleep labs are expensive and hard to book, so most cases go untested. Now researchers at Stanford say the fix might already be on your wrist. A new study found that smartwatch sleep apnea screening using a Samsung Galaxy Watch can flag moderate-to-severe cases with striking accuracy, giving people who snore through the night a reason to get checked out. The watch is not a diagnosis, the researchers stress, but it could shorten the path to one.

How the watch was put to the test

The latest test of smartwatch sleep apnea screening, reported by Medical Xpress, was published August 27 in the Journal of Clinical Sleep Medicine. It enrolled 147 adults with an average age of fifty-four. Every participant either already had a moderate-to-severe diagnosis or was considered highly likely to have the condition. Each wore a Galaxy Watch 6 with its sleep apnea feature switched on for two nights at the Stanford Health Care Sleep Medicine Center and three nights at home. The team then compared the watch readings against the gold standard: full overnight lab sleep studies.

At the watch's default setting, it picked out moderate-to-severe cases with 94 percent sensitivity and 67 percent specificity. In plain terms, the smartwatch sleep apnea screening caught nearly every true case, though about one flag in three turned out to be a false alarm. Tuning the threshold traded some detection power for precision, reaching 82 percent sensitivity and 95 percent specificity. Among the highest-risk participants, those whose blood oxygen dipped heavily during sleep, the watch missed no true cases and mislabeled no healthy sleepers.

Robson Capasso, the study's principal investigator and a Stanford professor of otolaryngology, said this kind of smartwatch sleep apnea screening could make testing far more accessible by bringing validated checks to something people already wear every night. The devices are not diagnostic tools, he noted, but they may speed up referrals toward proven treatments like positive airway pressure and weight management.

Arash Alavi, the study's lead author and director of software engineering at Stanford's Deep Data Research Center, pointed to the rigor of the testing: multiple nights, multiple measures, including the apnea-hypopnea index and hypoxic burden, which tracks how far blood oxygen falls during sleep. That kind of validation, he said, is exactly what clinical screening tools need. The work grew out of a research collaboration Samsung and Stanford announced in April 2025, aimed at improving the sleep apnea feature in Samsung's Health Monitor app, which had earlier received a De Novo authorization from the Food and Drug Administration.

Why a screening nudge matters

According to the American Academy of Sleep Medicine, obstructive sleep apnea happens when the upper airway repeatedly blocks during sleep, stopping or restricting breathing. It is common and serious, and untreated cases carry higher risks of stroke, heart attacks, depression and car crashes. Many cases stay undiagnosed, because a lab sleep study is expensive, inconvenient and easy to postpone. That is exactly where smartwatch sleep apnea screening could earn its place.

That is the gap smartwatch sleep apnea screening could fill. A phone cannot follow you to bed, but a watch already does, night after night. A flag from the wrist will not tell you that you have the disorder, but it can give you and your doctor a reason to look. Anyone with signs of apnea, like habitual snoring or gasping and choking in sleep, should talk to a doctor or contact an accredited sleep center for a proper evaluation.

Samsung and Stanford have said they want to go further, using the data to build AI-powered tools that move from one-off detection to daily monitoring of sleep health. For now, the message from the study is simpler: smartwatch sleep apnea screening looks reliable enough to earn a place in the conversation, and if your watch flags your sleep, take the hint and book the test.