1. An apparatus comprising: a touch screen; a camera; and a processor configured to: operate the apparatus with the camera turned off; turn on the camera based at least in part on a determination that no input has been received with respect to the apparatus for a specified period of time during the operation; obtain an image using the camera; determine whether the image includes information corresponding to a human facial feature; change a brightness of the touch screen based at least in part on a determination that the image does not include the information corresponding to the human facial feature; obtain another image with the camera based at least in part on a determination that no input has been received with respect to the apparatus for another specified period; and enter a sleep mode based at least in part on a determination that the another image does not include the information corresponding to the human facial feature.