You have the possibility to set manually or automatically the display brightness of your ScanWatch Light. To do so, perform the following steps: 

1. Open the Withings App.
2. Go to Devices.
3. Scroll to your ScanWatch Light.
4. Select All Settings.
5. Select Auto-brightness.
   The display brightness of your ScanWatch Light will vary automatically depending on the outside light. 
6. If you don't want to select the Auto-brightness mode, move the slider to set manually the display brightness of your ScanWatch Light.