This is a comment on Optimization of a spectrally tunable LED daylight simulator (Color Res Appl. 2017;42:419-423). We found that full widths at half maximums (FWHMs) of light-emitting diodes (LEDs) used in the six channels for daylight simulators given by Wei were 50nm, not 30nm. Therefore, it is impossible to implement AA-grade daylight simulators with six LED channels. By our simulation, it was found that at least seven LEDs channels with FWHMs of 30nm are required to produce a spectrally tunable daylight simulator with AA-grade by appropriate intensity combinations. Furthermore, the spectrally tunable AA-grade daylight simulators using six, five, and four channels were simulated. We have first reported that the scheme for the spectrally tunable daylight simulator with AA-grade using three, four, and five types of phosphors or quantum dots excited by an ultraviolet LED.