Medicine and Health Sciences Commons^™

The Spectral Sensitivity Of Human Circadian Phase Resetting And Melatonin Suppression To Light Changes Dynamically With Light Duration, Melissa A. St Hilaire, María L. Ámundadóttir, Shadab A. Rahman, Shantha M. W. Rajaratnam, Melanie Rüger, George C. Brainard, Charles A. Czeisler, Marilyne Andersen, Joshua J. Gooley, Steven W. Lockley

Department of Neurology Faculty Papers

Human circadian, neuroendocrine, and neurobehavioral responses to light are mediated primarily by melanopsin-containing intrinsically-photosensitive retinal ganglion cells (ipRGCs) but they also receive input from visual photoreceptors. Relative photoreceptor contributions are irradiance- and duration-dependent but results for long-duration light exposures are limited. We constructed irradiance-response curves and action spectra for melatonin suppression and circadian resetting responses in participants exposed to 6.5-h monochromatic 420, 460, 480, 507, 555, or 620 nm light exposures initiated near the onset of nocturnal melatonin secretion. Melatonin suppression and phase resetting action spectra were best fit by a single-opsin template with lambda_max at 481 and 483 …