Smartwatches, including the Apple Watch, can detect signs of Covid-19 before they even know you're sick, according to a new study. In a study called "Warrior Watch," researchers at Mount Sinai Medical Center found that the Apple Watch is able to detect small changes in a wearer's heart rate, which can indicate that they have contracted Covid-19 up to seven days before develop visible symptoms. . Specifically, the study looked at a metric called heart rate variability (HRV), the variation in time between each heartbeat, which is also a measure of how well a person's immune system is working. The participants wore Apple Watches equipped with special apps that measured changes in their HRV. "We already knew that markers of heart rate variability change as inflammation in the body grows, and Covid is an incredibly inflammatory event," said Dr. Robert Hirten, an assistant professor at the Icahn School of Medicine of New York and study author. CBS. "It allows us to predict that people are infected before they even realize it." A similar study from Stanford University found that 81% of Covid-19-positive participants who wore a variety of smartwatches — from Apple, Fitbit, Garmin and others — were told of an irregularity in their HRV until they' to nine days before the onset of significant symptoms. Perhaps the most difficult aspect of managing the global pandemic has been identifying people who contract Covid-19 but remain asymptomatic, meaning they have no symptoms but are still contagious (and thus unintentionally transmitting the virus). Studies like these have found that seemingly mundane consumer technology could play an important role in future pandemic management by making it easier for people to spot early signs of invisible symptoms. "Developing a way to identify people who might be sick before they know they are infected would really go a long way in managing Covid-19," said Dr. Hirten. “This technology allows us to not only track and predict health outcomes, but also to respond in a timely and remote manner, which is critical during a pandemic that forces people to stay apart.