NEW Irregular Heart Rhythm notifications are here! ❤️This feature analyses your heart rhythm during sleep or while at rest to let you know if it shows signs of Atrial fibrillation. #AFib is an irregular heart rhythm that can show up, well, irregularly & can be hard to detect during doctor visits. *** Irregular rhythm notifications are only available in select countries and with select Fitbit products; not intended for use by people under 22 years old or with other known arrhythmias. See fitbit.com/irregularrhythm for additional details.