The Ambient Sensor Drain
To help users improve their mental and physical health, newer models of the Apple Watch utilize the ambient light sensor built into the screen to actively monitor how much time you spend outside in the sun. This metric, called “Time in Daylight,” is recorded in the background and synced to the Health app on your iPhone. While tracking your sun exposure is theoretically useful, it requires the watch to constantly poll the light sensor throughout the entire day, resulting in unnecessary background battery drain. If you do not care about this highly specific health metric, you can disable the tracking entirely.
How to Turn Off Daylight Tracking
You can sever the light sensor’s connection to the Health app via the 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.
- Scroll down and tap on Health.
- Tap on Time in Daylight.
- Look for the master toggle switch labeled Time in Daylight.
- Toggle this switch to the Off position (the green background will disappear).
Conserving Power
The change takes effect immediately. The Apple Watch will completely stop polling the ambient light sensor for health data. While the screen will still use the sensor to adjust its brightness, the aggressive background tracking process will shut down, saving battery life and ensuring your outdoor movements are no longer actively logged to the Health app.