SleepWake is a smart phone app that tracks heart rate and tells wearers when they are too drowsy to drive, says founder and chief technology officer Tommy Tung Le.

It works by collecting a series of the wearer’s heart rate values through the optical sensor on the watch, then sending them to the server for analysis. “When you are drowsy…your heart rate variability (HRV) follows a distinctive pattern. By analyzing this pattern, it is possible to estimate your level of drowsiness wherever you are, with no special hardware other than your watch. Algorithms used to analyze HRV follow recommendations of European Society of Cardiology (ESC) and the North American Society of Pacing and Electrophysiology (NASPE). The current accuracy rate is more than 90%,” according to the manufacturer’s website.

Le earned his PhD in Computer Science from University of New South Wales in 2012. He’s passionate about applying big data on wearables to improve people’s fitness and well-being.