How your smartwatch and AI might detect early signs of illness

Some features are more clinically useful than others. Smartwatches and other wearables have moved far beyond just tracking your steps and heart rate. Many of today's versions can monitor everything from sleep and skin temperature to respiratory rate, blood oxygen, heart rate variability and even alert you to possible signs of sleep apnea . If you took Big Tech's marketing at face value, you might conclude that your smartwatch is on the verge of becoming a real-life Star Trek Tricorder. But how reliable are wearables for spotting early signs of illnesses or other medical conditions?