In 'Office at Night', the light comes from three sources: an overhead light, the lamp on the man's desk, which sheds a small puddle of intense light, and from a street-light shining in the open window on the right-hand side. Hopper reported that the overlap of the light from the ceiling fixture and the light from the exterior created particular technical difficulties, since they required him to use different shades of white to convey the idea of degrees of shadow. A careful examination of the corner behind the woman reveals the faint shadow that she casts in the weak light of the ceiling fixture, almost lost by the sharply-etched shadow of the filing cabinet in the brighter light of the street lamp.