<qa>  What is the NIFPs special nerve called?The human eye has a dual role, which is reflected by the various photo-receptors used for vision of images and colors ,Image forming photoreceptors IFP and for entrainment of our Biological clock located in the hypothalamus through the retinal ganglions known as non-image forming photoreceptors NIFP. The recently discovered new photo-pigment melanopsin which is sensitive to short wavelength SWL illumination exists in the-NIFP. The axons of the NIFP form a special nerve known as the Retino-hypothalamic-tract RHT that transfers the SWL signal to the biological clock resulting in suppression of pineal melatonin MLT production. This is the basic mechanism by which environmental lightdark cycles entrain the biological clock and transfer the message to organs, tissues and cell. 