Hold , and select > System > Display.

Brightness

Sets the brightness level of the display.

Timeout

Sets the length of time before the display turns off. You can use the Always On option to keep the time of day visible and turn off only the background. This option impacts the battery and display life (About the AMOLED Display).

NOTE: The Always On and Gesture settings are disabled during your sleep window to prevent the display from turning on while you are asleep.

Gesture

Sets the display to turn on when you rotate your wrist toward your body to view the device. You can use the Only During Activity option to use this feature only during timed activities. You can also adjust the gesture sensitivity to turn on the display more or less often.

During Activity

Sets the display to remain on or to turn it off based on the Timeout setting during a timed activity.