Many of us spend hours each day on our smartphones, whether it's texting friends or using our GPS for directions. And each of those actions leaves behind a digital breadcrumb. In this week's episode we're digging into our archives to explain how researchers are mining this data to improve health. JP Onnela, associate professor of biostatistics at Harvard T.H. Chan School of Public Health, will explain how harnessing smartphone information can be used to improve everything from our mental health to recovery from surgery.