An illumination apparatus suitable for inducing a biological and/or behavioural effect on a human or animal comprising: a first light source configured to emit light having a first spectral light distribution having a first main light intensity peak about a first peak wavelength providing light stimulation, wherein the first light source is a cold white light emitter and the first peak wavelength is within the range of 450 - 490 nm, a second light source configured to emit light having a second spectral light distribution having a second main light intensity peak about a second peak wavelength being different from the first peak wavelength, wherein the second light source is a cold white light emitter and the second peak wavelength is within the range of 440 - 450 nm or 490 - 500 nm, and wherein the first and second peak wavelengths are close in wavelength, within 10% of the visible spectral wavelength range, and a third light source configured to emit light having a third spectral light distribution having a third main light intensity peak about a third peak wavelength being different from the first peak wavelength and from the second peak wavelength, wherein the third light source is a warm white light emitter and the third peak wavelength is within the range of 500 - 700 nm, a further light source configured to emit light having a further spectral light distribution having a further main light intensity peak about a further peak wavelength being different from the first peak wavelength and from the second peak wavelength, wherein the further light has a main light intensity peak at a peak wavelength within the range of 580 - 630 nm, wherein the illumination apparatus is configured to provide adjustment of light intensity of the first light source and of light of the second light source, thereby providing a relative light intensity between the first light source and the second light source, wherein the illumination apparatus is configured to provide adjustment of light intensity of the third light source in to order to compensate for the adjusting of the relative light intensity between the first light source and the second light source, such that an overall light output from the illumination apparatus is maintained. a first light source configured to emit light having a first spectral light distribution having a first main light intensity peak about a first peak wavelength providing light stimulation, wherein the first light source is a cold white light emitter and the first peak wavelength is within the range of 450 - 490 nm, a second light source configured to emit light having a second spectral light distribution having a second main light intensity peak about a second peak wavelength being different from the first peak wavelength, wherein the second light source is a cold white light emitter and the second peak wavelength is within the range of 440 - 450 nm or 490 - 500 nm, and wherein the first and second peak wavelengths are close in wavelength, within 10% of the visible spectral wavelength range, and a third light source configured to emit light having a third spectral light distribution having a third main light intensity peak about a third peak wavelength being different from the first peak wavelength and from the second peak wavelength, wherein the third light source is a warm white light emitter and the third peak wavelength is within the range of 500 - 700 nm, a further light source configured to emit light having a further spectral light distribution having a further main light intensity peak about a further peak wavelength being different from the first peak wavelength and from the second peak wavelength, wherein the further light has a main light intensity peak at a peak wavelength within the range of 580 - 630 nm, wherein the illumination apparatus is configured to provide adjustment of light intensity of the first light source and of light of the second light source, thereby providing a relative light intensity between the first light source and the second light source, wherein the illumination apparatus is configured to provide adjustment of light intensity of the third light source in to order to compensate for the adjusting of the relative light intensity between the first light source and the second light source, such that an overall light output from the illumination apparatus is maintained.