Certain examples involve controlling a circadian impact of a lighting system. For instance, a lighting system includes a first lighting fixture. The first lighting fixture includes at least one lighting element to illuminate a first space and a first controller to control a first light output of the at least one lighting element. Additionally, the lighting system includes a first background circadian system that provides a first modifying factor to the first controller of the first lighting fixture. The first modifying factor is associated with a first circadian impact profile that specifies a first circadian impact level in the first space. Further, the first controller of the first lighting fixture controls the first light output based on the first modifying factor.