When does ScanWatch Light measure your heart rate?
When you use the Workout Mode, ScanWatch Light measures your heart rate continuously during the workout. In addition, ScanWatch Light measures your heart rate throughout the day when you’re motionless, and periodically when you’re walking. Since ScanWatch Light takes these background readings based on your activity, the time between these measurements will vary.
How does ScanWatch Light measure your heart rate?
The optical heart sensor in ScanWatch Light uses what is known as photoplethysmography (PPG). This technology is based on a very simple fact: Blood is red because it reflects red light and absorbs green light. ScanWatch Light uses green LED paired with light‑sensitive photodiodes to detect the amount of blood flowing through your wrist at any given moment. When your heart beats, the blood flow in your wrist — and the green light absorption — is greater. Between beats, it’s less. By flashing its LED lights thousands of times per minute, ScanWatch Light can calculate the number of times the heart beats each minute — your heart rate. The optical heart sensor supports a range of 30–210 beats per minute. In addition, the optical heart sensor is designed to compensate for low signal levels by increasing both LED brightness and sampling rate.
ScanWatch Light uses green LED lights to measure your heart rate during workouts.
- ScanWatch Light cannot detect heart attacks. If you ever experience chest pain, pressure, tightness, or what you think is a heart attack, call emergency services immediately.
- If you’re not feeling well, you should talk to your doctor even if you don’t get a notification. Symptoms such as a rapid, pounding, or fluttering heartbeat, dizziness, or fainting, can indicate a serious condition.
- Do not change your medication without talking to your doctor.
- ScanWatch Light uses green LED lights to take measurements. It is possible for you to notice it if your wristband is worn loose.
- Each time a heart rate measurement is launched (by you, automatically or during a workout session) LED lights are on, in general for 30 seconds.
- If the sensor remains constantly on, even when no measurement is launched nor scheduled, resetting the watch by pressing and holding the button for 20 seconds should resolve the problem.