You probably glance at your watch dozens of times a day. Many of us also keep it on at night, more out of habit than any real plan. But what if that same strap on your wrist could flag a serious health problem while you sleep?
A new Stanford Health Care study suggests it can. Researchers tested the Samsung Galaxy Watch 6 against hospital sleep tests in 147 adults. The watch picked up moderate-to-severe sleep apnea with 94 percent accuracy, according to a study in the Journal of Clinical Sleep Medicine.
Sleep apnea is a condition where your breathing stops and starts over and over during the night. The pauses pull oxygen from the blood and jolt you out of deep sleep, often without you noticing.
An estimated 80 percent of cases go undiagnosed. A 2019 analysis in The Lancet Respiratory Medicine estimated that 936 million adults worldwide have obstructive sleep apnea, nearly ten times earlier figures.
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How the Stanford team tested the watch
The study enrolled 147 adults with an average age of 54. Most had a prior diagnosis of moderate-to-severe sleep apnea or clear signs pointing toward it.
Each person wore the Galaxy Watch 6 for two nights at the Stanford Health Care Sleep Medicine Center. They also wore it for three more nights at home.
At the sleep center, the watch's readings were compared against the gold-standard exam called polysomnography. That is the overnight test where sensors track breathing, heart rate and brain activity in a lab.
The watch flagged moderate-to-severe apnea with 94 percent accuracy. Among people with the heaviest overnight drops in blood oxygen, the watch correctly identified every single case.
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Robson Capasso, the study's principal investigator and professor of otolaryngology at Stanford University, said consumer smartwatches can make sleep apnea screening more accessible. The finding helps identify people at risk for moderate-to-severe disease, he said.
The devices are not diagnostic, he said. They are a screening aid that can shorten the path to a proper sleep study and to treatments such as a nightly breathing device or weight management.
Why catching it early matters
Left untreated, sleep apnea is tied to a long list of serious problems. The Stanford researchers note that it raises the risk of heart attack, stroke, depression and motor vehicle accidents.
It also appears to accelerate changes in the brain. A 2026 study in Alzheimer's & Dementia that followed older adults for a decade found untreated sleep apnea was linked to faster cognitive decline than seen in people on standard CPAP treatment.
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That is why the goal of the smartwatch is to flag risk earlier. If your watch, your bed partner or your own daytime exhaustion points toward loud snoring or gasping at night, mention it to your doctor. A full sleep study is still the only way to confirm the diagnosis.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.