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Author Stevens, R.G.
Title Artificial lighting in the industrialized world: circadian disruption and breast cancer Type Journal Article
Year 2006 Publication Cancer Causes & Control : CCC Abbreviated Journal Cancer Causes Control
Volume 17 Issue 4 Pages 501-507
Keywords Human Health; Alcohol Drinking/adverse effects; Animals; Breast Neoplasms/*etiology; Chronobiology Disorders/*etiology/physiopathology; Circadian Rhythm; Developing Countries; Female; Humans; Lighting/*adverse effects; Melatonin/metabolism; Risk Factors; Suprachiasmatic Nucleus/physiopathology
Abstract Breast cancer risk is high in industrialized societies, and increases as developing countries become more Westernized. The reasons are poorly understood. One possibility is circadian disruption from aspects of modern life, in particular the increasing use of electric power to light the night, and provide a sun-free environment during the day inside buildings. Circadian disruption could lead to alterations in melatonin production and in changing the molecular time of the circadian clock in the suprachiasmatic nuclei (SCN). There is evidence in humans that the endogenous melatonin rhythm is stronger for persons in a bright-day environment than in a dim-day environment; and the light intensity necessary to suppress melatonin at night continues to decline as new experiments are done. Melatonin suppression can increase breast tumorigenesis in experimental animals, and altering the endogenous clock mechanism may have downstream effects on cell cycle regulatory genes pertinent to breast tissue development and susceptibility. Therefore, maintenance of a solar day-aligned circadian rhythm in endogenous melatonin and in clock gene expression by exposure to a bright day and a dark night, may be a worthy goal. However, exogenous administration of melatonin in an attempt to achieve this goal may have an untoward effect given that pharmacologic dosing with melatonin has been shown to phase shift humans depending on the time of day it's given. Exogenous melatonin may therefore contribute to circadian disruption rather than alleviate it.
Address (up) University of Connecticut Health Center, Farmington, CT 06030-6325, USA. bugs@neuron.uchc.edu
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0957-5243 ISBN Medium
Area Expedition Conference
Notes PMID:16596303 Approved no
Call Number LoNNe @ kagoburian @ Serial 818
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