Backlight Settings
Press Menu, and select Settings > System > Backlight.
Mode: Sets the backlight to turn on for interactions. Interactions include the buttons, touchscreen, and notifications.
Gesture: Sets the backlight to turn on for wrist gestures. Gestures include rotating your wrist toward your body to view the device. You can use the Only During Activity option to use gestures only during timed activities.
Timeout: Sets the length of time before the backlight turns off.
Brightness: Sets the brightness level of the backlight.