A lighting device includes a lighting module, a storage module storing light data sets corresponding respectively to successive time points of a cycling period, and a processing unit. In a routine mode, the processing unit controls the lighting module to emit light and to successively change color of light at the successive time points of the cycling period. In an adjustment mode, the processing unit reads from the storage device one light data set corresponding to the time point indicated by a time signal from an input device, adjusts the light data set according to a color signal from the input device, and controls the lighting module to emit light based on the adjusted light data set.
