a method , and device incorporating the method , permits adjustment of the on time of a light source that illuminates a display within a handheld wireless communications device . the on time may be adjusted by the amount of information to be displayed , the font size of the information , the behavioral characteristics of the end user , the type of viewing activity , and the like . an optional dim mode permits the end user to be made aware that the light illuminating the display is about to be shut off .