I’ve been wearing some version of a health tracker on my body since 2009. Back then, it was a clunky pedometer strapped to my hip during track practice, and I thought it was sorcery. Fifteen years and roughly a dozen wearables later, I’m here to tell you that the war happening right now in smart rings isn’t about sensors anymore. It’s about which company built the brain that actually makes sense of all that data while you sleep. Seven days ago, Ultrahuman pushed something called the Emerald update to every ring they’ve ever sold. I woke up that morning to…