Alliance for Lighting Information

Melanopsin and Human Health

by David M. Keith

Since 2002, information has been developed about the role of retinal ganglion cells in the control of melatonin. Dr. Pauley's summary of the science as of 2004 is available from Medical Hypotheses (v63i4 Pages 588-596).

Recent research has shown that:
- melatonin is a neurochemical that controls the diurnal (day/night) cycle for most animals including humans
- disruption of the day/night cycle corresponds to increased risks for some health conditions including some forms of cancer
- melatonin - as an "anti-oxidant" - may have a role in reducing cancers
- radiant energy onto the retina can effect the production of the neurochemical melatonin
- some retinal ganglion cells (RGCs) are non-visual photoreceptors
- the photopigment found in RGCs has been dubbed "melanopsin"
- the sensitivity function for melanopsin peaks around 464 nm and corresponds to sky blue

The following diagram shows the relative sensitivity of melanopsin (as developed by J. Hollan) as the blue line on the left side, along with the conventional photopic (white and gray) and scotopic (black) sensitivity functions.

Additional Links

LIGHT, ENDOCRINE SYSTEMS AND CANCER: Facts and Research Perspectives from International Symposium May 2–3, 2002 University of Cologne, Germany and NEUROENDOCRINOLOGY LETTERS

Study: Melatonin Stops Light-at-night Breast Cancer Burden is a press release from NEUROENDOCRINOLOGY LETTERS

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