LED lights are all around us. They illuminate our homes, our cars, and our businesses. But did you know they are vital in the world of medicine, too? Apple and researchers at Stanford Medicine are collaborating on a study to see if the Apple Watch heart rate sensor is capable of identifying irregular heart rhythms in patients with atrial fibrillation—typically referred to as AFib. AFib is the leading cause of stroke. In fact, it is responsible for in excess of 130,000 deaths and more than 750,000 hospital stays for Americans every single year. And sadly, most of these patients never experience even one symptom. This means AFib typically goes undiagnosed. The Apple Watch calculates the wearer’s heart rate and rhythm through the use of green LED lights that flash hundreds of times each second. Light sensitive photodiodes work in conjunction with these lights to detect how much blood is flowing through the wearer’s wrist. A new Apple Heart Study app uses this existing technology to identify an irregular rhythm in the heart. Apple COO Jeff Williams touted the company’s efforts and recent collaboration with Stanford. “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,” he said. “Working alongside the medical community, not only can we can inform people of certain health conditions, we also hope to advance discoveries in heart science.” Those patients involved in this study will receive a notification on their Apple Watch and iPhone that an irregular heart rhythm has been detected. They will then visit with a doctor who is also taking part in the study. Who would have imagined in 1962 when Earl Holonyak, Jr., who invented the LED light while working for General Electric, that it would one day be implemented in medical science as a way to save lives? The green diodes that now go into the creation of the green LED lights that measure heart rate and rhythm were the third of the diodes he invented. They were preceded by red and pale yellow. Given the amazing innovations that now involve LED lights, it’s hard to imagine how else they might be used in the future. It’s obvious that when teamed with professionals in the medical field, that they will be used for countless benefits well beyond their initial intended use.