Breather is a gamified, biofeedback exercise on the Happify app that trains users to adjust and regulate their heart rate variability (HRV ), calming the nervous system. Below is an infographic detailing the findings from two different studies initiated by Twill and conducted by researchers at Washington University and the University of California, Irvine. The first study validated Breather’s accuracy in measuring HRV, and the second showed its effectiveness as a tool for improving stress recovery.