The GBA uses an LCD screen, so yes, you need to find a good source of light. Using it outside in direct sunlight tho isnt a good idea (as it sends the picture quality weird and hurts ur eyes) but having your back to a window or light or something helps (I have a spotlight on the wall pointing just above my bed, so I sit on it with my back to the spotlight and it lights up the screen fine. Directly pointing at the GBA tho will just give glare). Best to experiment to find a comfortable, well lit setup really.