Controlling a lighting device having at least two electric light sources

A method may include supplying electric power to a first light source and a second light source of at least two light sources by at least one ballast so that the first light source and the second light source emit a first source light and a second source light with a first and second spectral light distribution, respectively. The method further includes superimposing the first and second source light using an optical unit such that the lighting device outputs light with a spectral superposition light distribution. The method further includes detecting the light outputted from the lighting device using a light distribution sensor that provides a sensor signal corresponding to a spectral light distribution of the detected light. The method further includes comparing the sensor signal to a predefined spectral light distribution and adjusting the electric power supplied to the respective light source by the ballast based on the comparison.