A display apparatus includes a display panel, a backlight unit, a backlight control circuit, sensors, a read-out circuit and a sensor auxiliary circuit. The display panel includes pixels and displays an image. The backlight unit includes a first light source which emits a first light in a infrared light range. The backlight control circuit controls a brightness of the first light source. The sensors sense an external signal and outputs first sensing signals. The read-out circuit outputs the first sensing signals as second sensing signals. The sensor auxiliary circuit compares a maximum value and a minimum value of the second sensing signals and provides a brightness control signal to the backlight control circuit based on the compared difference to control the brightness of the first light source.