Get your fitness journey back on track with the Fitbit Charge 6. It has a whopping 7 days of battery life so you can track an entire weeks' worth of data without running out of juice. Even when you're asleep, your Fitbit is monitoring your heart rate, blood oxygen, skin temperature and more, for a well-rounded overview of your health. With a daily sleep score, you'll be able to tell how soundly your slept which means you can improve your health from all angles.