Apple (AAPL) Watches can now detect irregular heart rhythms.

The iPhone maker on Thursday introduced the Apple Heart Study app, dubbed "a first-of-its-kind research study using Apple Watch's heart rate sensor to collect data on irregular heart rhythms and notify users who may be experiencing atrial fibrillation (AFib)."

The app calculates a person's heartbeat using LED lights flashing hundreds of times per second powered by the sensor of an Apple Watch, along with light-sensitive photodiodes, to identify the blood flow through one's wrist.

Then using various algorithms, the watch isolates heart rhythms from other sounds, and the Apple Heart Study app applies this technology to detect an irregular heart rhythm.

"Every week we receive incredible customer letters about how Apple Watch has affected their lives, including learning that they have AFib. These stories inspire us and we're determined to do more to help people understand their health," said Jeff Williams, Apple's COO. "Working alongside the medical community, not only can we inform people of certain health conditions, we also hope to advance discoveries in heart science."

The Apple Heart Study app is available in the U.S. App Store to consumers who are 22 years or older and have an Apple Watch Series 1 or later.

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