NEW YORK,NY - MARCH 1: Fitbit unveils Alta HR, the world's slimmest fitness wristband with continuous heart rate, as well as two new sleep tracking features "Sleep Stages and Sleep Insights " at an event hosted by actress and dancer Julianne Hough on March 1, 2017 at SWERVE Fitness in New York. (Photo by Dave Kotinsky/Getty Images for Fitbit)
