Action spectra of ipRGCs and of melanopsin photopigment peak around 480 nm in the blue portion of the visible spectrum and match peak sensitivities of circadian photoentraiment, pupillary light reflex, light suppression of melatonin hormone, and light exacerbation of migraine pain.6 The NIF responses are attenuated, not eliminated, in melanopsin-deficient mice, and are completely abolished in mice that lack both melanopsin and functional outer retina photoreceptors. This evidence concerns the gene OPN4 and migraine disorder.