The Apple Watch calculates your resting heart rate by monitoring your heart rate throughout the day. When it detects that you are still and relaxed, it takes a reading. To get the most accurate resting heart rate, it's best to wear your Apple Watch while you're asleep, as this is when your heart rate is typically at its lowest.
The watch uses its optical heart sensor to detect blood flow in your wrist. As your heart beats, blood surges in your wrist. Each surge causes a tiny amount of light to be reflected back to the sensor. The sensor detects these surges and determines your heart rate.
Your resting heart rate is measured when you are still and relaxed. This includes periods of inactivity, light activity, and sleep. The Apple Watch takes multiple readings during these periods and averages them to provide a more reliable resting heart rate measurement.
Apple Watch Resting Heart Rate Influencing Factors
Several factors can influence your resting heart rate, and while the Apple Watch can track it, understanding these external factors is key: