The Photoplethysmography Sensor
The Apple Watch features an integrated optical heart rate sensor. By default, the operating system executes a background tracking algorithm that periodically flashes green LEDs against your skin to measure your resting heart rate (BPM) throughout the day, and continuously during a workout. For users who strictly use the Apple Watch for notifications and cellular connectivity, or for those who demand maximum multi-day battery life and have absolutely no interest in continuously logging their cardiovascular metrics to the Health app, firing these high-intensity LEDs is a massive waste of power. You must paralyze this optical array.
How to Disable the Heart Rate Sensor
You can permanently sever the background tracking daemon via the global Privacy settings.
- Open the Settings app directly on your Apple Watch (the grey gear icon).
- Scroll down the main list and tap on Privacy & Security.
- Tap on Health.
- Tap on Heart Rate.
- Locate the master toggle switch labeled Heart Rate.
- Toggle this switch to the Off position (the green background will disappear).
Total Cardiovascular Isolation
The change is instantaneous. The Apple Watch will completely sever its internal connection to the photoplethysmography hardware array for the purpose of background sampling. The background machine learning daemon responsible for scheduling the sensor sweeps is permanently terminated. You can now walk, run, or sleep with the watch on, and the operating system will absolutely refuse to activate the green LEDs on your wrist. This guarantees that your battery capacity is strictly reserved for core computing functions, rather than unnecessary cardiovascular logging.