Human Melatonin Suppression in Response to Silent Substitution Stimuli of Photoreceptors

Abstract

It is important to understand how photoreceptors contribute to non-image-forming visual functions to enable the design of light environments that support optimal circadian rhythm regulation. The purpose of this study was to investigate the contribution of melanopsin-expressing ganglion cells (mRGCs) to circadian rhythm regulation using the silent substitution method, which modulates light stimulus levels to each photoreceptor (mRGC and three types of cones). Night-time saliva melatonin concentrations were measured to assess its contribution to circadian rhythms. We found that melatonin suppression was significantly affected by mRGC stimulation which was modulated by the silent substitution method, especially at time early in melatonin secretion.