This was recently discovered by Michael Snyder at Stanford University in California where he was running an experiment that tested the reliability of the sensors. Everything was going fine when one day they started to show abnormal readings, such as an elevated heart rate, increase in skin temperature, and a drop in his oxygen levels in his blood.
Snyder suspected that he might have caught Lyme disease from one of his trips, and following a mild fever, he asked his doctor for the antibiotic doxycycline which is used to treat the disease, and soon enough his symptoms cleared up within a day. According to Snyder, “Once these wearables collect enough data to know what your normal baseline readings are, they can get very good at sensing when something’s amiss.”
He adds, “We think that if your heart rate and skin temperature are elevated for about 2 hours, there’s a strong chance you’re getting sick.” Of course making a trip to the doctor is probably the best idea, but it looks your smartwatch could at the very least let you know ahead of time that something could be off, thus letting you better prepare yourself.