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Author Hansen, J.; Lassen, C.F.
Title Nested case-control study of night shift work and breast cancer risk among women in the Danish military Type Journal Article
Year 2012 Publication Occupational and Environmental Medicine Abbreviated Journal Occup Environ Med
Volume 69 Issue 8 Pages (down) 551-556
Keywords Adult; Aged; Aged, 80 and over; Breast Neoplasms/*etiology; Case-Control Studies; *Circadian Rhythm; Denmark/epidemiology; Female; Humans; Logistic Models; Middle Aged; Military Personnel; *Occupations; Odds Ratio; Risk Factors; *Sunlight; *Work; *Work Schedule Tolerance; oncogenesis
Abstract OBJECTIVES: Growing but limited evidence suggests that night shift work is associated with breast cancer. The authors conducted a nationwide case-control study nested within a cohort of 18,551 female military employees born in 1929-1968 to investigate the risk for breast cancer after night shift work and to explore the role of leisure time sun exposure and diurnal preference. METHODS: The authors documented 218 cases of breast cancer (1990-2003) and selected 899 age-matched controls from the cohort by incidence density sampling. Information on shift work, sun exposure habits, diurnal preference and other potential confounders was obtained from a structured questionnaire. ORs were estimated by multivariate conditional logistic regression. RESULTS: Overall, the authors observed an adjusted OR of 1.4 (95% CI 0.9 to 2.1) among women with ever compared with never night shifts. The RR for breast cancer tended to increase with increasing number of years of night shift work (p=0.03) and with cumulative number of shifts (p=0.02),with a neutral risk for fewer than three night shifts per week. The OR for the group with the highest tertile of cumulative exposure was 2.3 (95% CI 1.2 to 4.6). The most pronounced effect of night shift work on breast cancer risk was observed in women with morning chronotype preference and intense night shifts (OR=3.9, 95% CI 1.6 to 9.5). Night shift workers tended to sunbathe more frequently than day workers. CONCLUSIONS: The results indicate that frequent night shift work increases the risk for breast cancer and suggest a higher risk with longer duration of intense night shifts. Women with morning preference who worked on night shifts tended to have a higher risk than those with evening preference.
Address Institute of Cancer Epidemiology, Danish Cancer Society, Strandboulevarden 49, Copenhagen DK2100, Denmark. johnni@cancer.dk
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Series Volume Series Issue Edition
ISSN 1351-0711 ISBN Medium
Area Expedition Conference
Notes PMID:22645325 Approved no
Call Number IDA @ john @ Serial 156
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Author Schoech, S.J.; Bowman, R.; Hahn, T.P.; Goymann, W.; Schwabl, I.; Bridge, E.S.
Title The effects of low levels of light at night upon the endocrine physiology of western scrub-jays (Aphelocoma californica) Type Journal Article
Year 2013 Publication Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology Abbreviated Journal J Exp Zool A Ecol Genet Physiol
Volume 319 Issue 9 Pages (down) 527-538
Keywords Animals; Corticosterone/blood; Ecosystem; Female; *Light; Male; Melatonin/blood; Passeriformes/*physiology; *Photoperiod; Reproduction/*physiology; Testosterone/blood
Abstract Florida scrub-jays (Aphelocoma coerulescens) in the suburbs breed earlier than jays in native habitat. Amongst the possible factors that influence this advance (e.g., food availability, microclimate, predator regime, etc.), is exposure to artificial lights at night (LAN). LAN could stimulate the reproductive axis of the suburban jays. Alternatively, LAN could inhibit pineal melatonin (MEL), thus removing its inhibitory influence on the reproductive axis. Because Florida scrub-jays are a threatened species, we used western scrub-jays (Aphelocoma californica) to investigate the effects of LAN upon reproductive hormones and melatonin. Jays were held under conditions in which the dark-phase of the light:dark cycle was without illumination and then under low levels of LAN. Under both conditions, birds were exposed first to short-days (9.5L:14.5D) that were gradually increased to long-days (14.5L:9.5D). At various times, blood samples were collected during the light part of the cycle to measure reproductive hormones (luteinizing hormone, LH; testosterone, T; and estradiol, E2 ). Similarly, samples to assess melatonin were collected during the dark. In males, LAN caused a depression in LH levels and levels were approximately 4x greater under long- than short-days. In females, there was no effect of LAN or photoperiod upon LH. LAN resulted in depressed T levels in females, although there was no effect on T in males. E2 levels in both sexes were lower under LAN than under an unlighted dark-phase. Paradoxically, MEL was higher in jays under LAN, and under long-days. MEL did not differ by sex. LAN disrupted the extraordinarily strong correlation between T and E2 that existed under unlighted nocturnal conditions. Overall, our findings fail to support the hypothesis that LAN stimulates the reproductive axis. Rather, the data demonstrate that LAN tends to inhibit reproductive hormone secretion, although not in a consistent fashion between the sexes.
Address Department of Biological Sciences, University of Memphis, Memphis, Tennessee
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-5223 ISBN Medium
Area Expedition Conference
Notes PMID:23970442 Approved no
Call Number IDA @ john @ Serial 37
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Author Spivey, A.
Title Light at night and breast cancer risk worldwide Type
Year 2010 Publication Environmental Health Perspectives Abbreviated Journal Environ Health Perspect
Volume 118 Issue 12 Pages (down) a525
Keywords Human Health; Breast Neoplasms/epidemiology/*etiology/prevention & control; Female; Humans; Lighting/*adverse effects; Male; Prostatic Neoplasms/epidemiology/*etiology/prevention & control; Risk Factors
Abstract
Address
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Language English Summary Language Original Title
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Series Volume Series Issue Edition
ISSN 0091-6765 ISBN Medium
Area Expedition Conference
Notes PMID:21123149; PMCID:PMC3002207 Approved no
Call Number LoNNe @ kagoburian @ Serial 813
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Author Vollmer, C.; Michel, U.; Randler, C.
Title Outdoor light at night (LAN) is correlated with eveningness in adolescents Type Journal Article
Year 2012 Publication Chronobiology International Abbreviated Journal Chronobiol Int
Volume 29 Issue 4 Pages (down) 502-508
Keywords Adolescent; *Adolescent Behavior/drug effects; Biological Clocks; Central Nervous System Stimulants/administration & dosage; *Circadian Rhythm/drug effects; Computers; Cross-Sectional Studies; Female; Germany; Humans; *Light; Lighting; Male; *Photic Stimulation; *Photoperiod; Questionnaires; *Sleep/drug effects; Television; Time Factors; Video Games; *Wakefulness/drug effects
Abstract External zeitgebers synchronize the human circadian rhythm of sleep and wakefulness. Humans adapt their chronotype to the day-night cycle, the strongest external zeitgeber. The human circadian rhythm shifts to evening-type orientation when daylight is prolonged into the evening and night hours by artificial light sources. Data from a survey of 1507 German adolescents covering questions about chronotype and electronic screen media use combined with nocturnal satellite image data suggest a relationship between chronotype and artificial nocturnal light. Adolescents living in brightly illuminated urban districts had a stronger evening-type orientation than adolescents living in darker and more rural municipalities. This result persisted when controlling for time use of electronic screen media, intake of stimulants, type of school, age, puberty status, time of sunrise, sex, and population density. Time spent on electronic screen media use-a source of indoor light at night-is also correlated with eveningness, as well as intake of stimulants, age, and puberty status, and, to a lesser degree, type of school and time of sunrise. Adequate urban development design and parents limiting adolescents' electronic screen media use in the evening could help to adjust adolescents' zeitgeber to early school schedules when they provide appropriate lighting conditions for daytime and for nighttime.
Address Department of Biology, University of Education Heidelberg, Germany. vollmer@ph-heidelberg.de
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0742-0528 ISBN Medium
Area Expedition Conference
Notes PMID:22214237 Approved no
Call Number IDA @ john @ Serial 150
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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 (down) 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 University of Connecticut Health Center, Farmington, CT 06030-6325, USA. bugs@neuron.uchc.edu
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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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