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Author Hurley, S.; Nelson, D.O.; Garcia, E.; Gunier, R.; Hertz, A.; Reynolds, P.
Title (up) A cross-sectional analysis of light at night, neighborhood sociodemographics and urinary 6-sulfatoxymelatonin concentrations: implications for the conduct of health studies Type Journal Article
Year 2013 Publication International Journal of Health Geographics Abbreviated Journal Int J Health Geogr
Volume 12 Issue 1 Pages 39
Keywords circadian disruption; 6-sulftoxymelatonin; melatonin; aMT6s, DMSP; light at night
Abstract BACKGROUND: There is accumulating evidence that circadian disruption, mediated by alterations in melatonin levels, may play an etiologic role in a wide variety of diseases. The degree to which light-at-night (LAN) and other factors can alter melatonin levels is not well-documented. Our primary objective was to evaluate the degree to which estimates of outdoor environmental LAN predict 6-sulftoxymelatonin (aMT6s), the primary urinary metabolite of melatonin. We also evaluated other potential behavioral, sociodemographic, and anthropomorphic predictors of aMT6s. METHODS: Study participants consisted of 303 members of the California Teachers Study who provided a 24-hour urine specimen and completed a self-administered questionnaire in 2000. Urinary aMT6s was measured using the Buhlmann ELISA. Outdoor LAN levels were estimated from satellite imagery data obtained from the U.S. Defense Meteorological Satellite Program's (DMSP) Operational Linescan System and assigned to study participants' geocoded residential address. Information on other potential predictors of aMT6s was derived from self-administered surveys. Neighborhood socioeconomic status (SES) was based on U.S. Census block group data. RESULTS: Lower aMT6s levels were significantly associated with older age, shorter nights, and residential locations in lower SES neighborhoods. Outdoor sources of LAN estimated using low-dynamic range DMSP data had insufficient variability across urban neighborhoods to evaluate. While high-dynamic range DMSP offered much better variability, it was not significantly associated with urinary aMT6s. CONCLUSIONS: Future health studies should utilize the high-dynamic range DMSP data and should consider other potential sources of circadian disruption associated with living in lower SES neighborhoods.
Address
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 1476-072X ISBN Medium
Area Expedition Conference
Notes PMID:24127816; PMCID:PMC3766028 Approved no
Call Number IDA @ john @ Serial 142
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Author Robert, K.A.; Lesku, J.A.; Partecke, J.; Chambers, B.
Title (up) Artificial light at night desynchronizes strictly seasonal reproduction in a wild mammal Type Journal Article
Year 2015 Publication Proceedings. Biological Sciences / The Royal Society Abbreviated Journal Proc Biol Sci
Volume 282 Issue 1816 Pages
Keywords Animals; Macropus eugenii; anthropogenic disturbance; circadian disruption; light pollution; melatonin; trophic mismatch; ecology; wildlife
Abstract Change in day length is an important cue for reproductive activation in seasonally breeding animals to ensure that the timing of greatest maternal investment (e.g. lactation in mammals) coincides with favourable environmental conditions (e.g. peak productivity). However, artificial light at night has the potential to interfere with the perception of such natural cues. Following a 5-year study on two populations of wild marsupial mammals exposed to different night-time levels of anthropogenic light, we show that light pollution in urban environments masks seasonal changes in ambient light cues, suppressing melatonin levels and delaying births in the tammar wallaby. These results highlight a previously unappreciated relationship linking artificial light at night with induced changes in mammalian reproductive physiology, and the potential for larger-scale impacts at the population level.
Address School of Animal Biology, The University of Western Australia, Perth 6009, Australia
Corporate Author Thesis
Publisher Royal Society Place of Publication Editor
Language English Summary Language English Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0962-8452 ISBN Medium
Area Expedition Conference
Notes PMID:26423847 Approved no
Call Number IDA @ john @ Serial 1286
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Author Vetter, C.; Juda, M.; Lang, D.; Wojtysiak, A.; Roenneberg, T.
Title (up) Blue-enriched office light competes with natural light as a zeitgeber Type Journal Article
Year 2011 Publication Scandinavian Journal of Work, Environment & Health Abbreviated Journal Scand J Work Environ Health
Volume 37 Issue 5 Pages 437-445
Keywords *Circadian Rhythm; *Color; Humans; *Lighting; *Occupational Health; Sleep; Wakefulness; blue light; circadian disruption; Circadian rhythm; sleep
Abstract OBJECTIVES: Circadian regulation of human physiology and behavior (eg, body temperature or sleep-timing), depends on the “zeitgeber” light that synchronizes them to the 24-hour day. This study investigated the effect of changing light temperature at the workplace from 4000 Kelvin (K) to 8000 K on sleep-wake and activity-rest behavior. METHODS: An experimental group (N=27) that experienced the light change was compared with a non-intervention group (N=27) that remained in the 4000 K environment throughout the 5-week study period (14 January to 17 February). Sleep logs and actimetry continuously assessed sleep-wake behavior and activity patterns. RESULTS: Over the study period, the timing of sleep and activity on free days steadily advanced parallel to the seasonal progression of sunrise in the non-intervention group. In contrast, the temporal pattern of sleep and activity in the experimental group remained associated with the constant onset of work. CONCLUSION: The results suggest that artificial blue-enriched light competes with natural light as a zeitgeber. While subjects working under the warmer light (4000 K) appear to entrain (or synchronize) to natural dawn, the subjects who were exposed to blue-enriched (8000 K) light appear to entrain to office hours. The results confirm that light is the dominant zeitgeber for the human clock and that its efficacy depends on spectral composition. The results also indicate that blue-enriched artificial light is a potent zeitgeber that has to be used with diligence.
Address Institute for Medical Psychology, Centre of Chronobiology, Ludwig-Maximilians-Universitat, Munich, Germany
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 0355-3140 ISBN Medium
Area Expedition Conference
Notes PMID:21246176 Approved no
Call Number IDA @ john @ Serial 350
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Author Dauchy, R.T.; Xiang, S.; Mao, L.; Brimer, S.; Wren, M.A.; Yuan, L.; Anbalagan, M.; Hauch, A.; Frasch, T.; Rowan, B.G.; Blask, D.E.; Hill, S.M.
Title (up) Circadian and melatonin disruption by exposure to light at night drives intrinsic resistance to tamoxifen therapy in breast cancer Type Journal Article
Year 2014 Publication Cancer Research Abbreviated Journal Cancer Res
Volume 74 Issue 15 Pages 4099-4110
Keywords *Cancer; breast cancer; melatonin; endocrinology; tamoxifen; *Circadian Rhythm; circadian disruption; human health; epidemiology
Abstract Resistance to endocrine therapy is a major impediment to successful treatment of breast cancer. Preclinical and clinical evidence links resistance to antiestrogen drugs in breast cancer cells with the overexpression and/or activation of various pro-oncogenic tyrosine kinases. Disruption of circadian rhythms by night shift work or disturbed sleep-wake cycles may lead to an increased risk of breast cancer and other diseases. Moreover, light exposure at night (LEN) suppresses the nocturnal production of melatonin that inhibits breast cancer growth. In this study, we used a rat model of estrogen receptor (ERalpha(+)) MCF-7 tumor xenografts to demonstrate how altering light/dark cycles with dim LEN (dLEN) speed the development of breast tumors, increasing their metabolism and growth and conferring an intrinsic resistance to tamoxifen therapy. These characteristics were not observed in animals in which the circadian melatonin rhythm was not disrupted, or in animals subjected to dLEN if they received nocturnal melatonin replacement. Strikingly, our results also showed that melatonin acted both as a tumor metabolic inhibitor and a circadian-regulated kinase inhibitor to reestablish the sensitivity of breast tumors to tamoxifen and tumor regression. Together, our findings show how dLEN-mediated disturbances in nocturnal melatonin production can render tumors insensitive to tamoxifen. Cancer Res; 74(15); 4099-110. (c)2014 AACR.
Address Departments of Structural and Cellular Biology and Tulane Cancer Center and Louisiana Cancer Research Consortium; Tulane Circadian Cancer Biology Group; and
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 0008-5472 ISBN Medium
Area Expedition Conference
Notes PMID:25062775; PMCID:PMC4119539 Approved no
Call Number IDA @ john @ Serial 355
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Author He, C.; Anand, S.T.; Ebell, M.H.; Vena, J.E.; Robb, S.W.
Title (up) Circadian disrupting exposures and breast cancer risk: a meta-analysis Type Journal Article
Year 2014 Publication International Archives of Occupational and Environmental Health Abbreviated Journal Int Arch Occup Environ Health
Volume 88 Issue 5 Pages 533-547
Keywords Human Health; Circadian disruption; Breast cancer; Meta-analysis; Oncogenesis; BrCA; shift work; meta-analysis
Abstract PURPOSE: Shift work, short sleep duration, employment as a flight attendant, and exposure to light at night, all potential causes of circadian disruption, have been inconsistently associated with breast cancer (BrCA) risk. The aim of this meta-analysis is to quantitatively evaluate the combined and independent effects of exposure to different sources of circadian disruption on BrCA risk in women. METHODS: Relevant studies published through January 2014 were identified by searching the PubMed database. The pooled relative risks (RRs) and corresponding 95 % confidence intervals (CIs) were estimated using fixed- or random effects models as indicated by heterogeneity tests. Generalized least squares trend test was used to assess dose-response relationships. RESULTS: A total of 28 studies, 15 on shift work, 7 on short sleep duration, 3 on flight attendants, and 6 on light at night were included in the analysis. The combined analysis suggested a significantly positive association between circadian disruption and BrCA risk (RR = 1.14; 95 % CI 1.08-1.21). Separate analyses showed that the RR for BrCA was 1.19 (95 % CI 1.08-1.32) for shift work, 1.120 (95 % CI 1.119-1.121) for exposure to light at night, 1.56 (95 % CI 1.10-2.21) for employment as a flight attendant, and 0.96 (95 % CI 0.86-1.06) for short sleep duration. A dose-response analysis showed that each 10-year increment of shift work was associated with 16 % higher risk of BrCA (95 % CI 1.06-1.27) based on selected case-control studies. No significant dose-response effects of exposure to light at night and sleep deficiency were found on BrCA risk. CONCLUSIONS: Our meta-analysis demonstrates that circadian disruption is associated with an increased BrCA risk in women. This association varied by specific sources of circadian disrupting exposures, and a dose-response relationship remains uncertain. Therefore, future rigorous prospective studies are needed to confirm these relationships.
Address Department of Epidemiology and Biostatistics, College of Public Health, University of Georgia, 101 Buck Road, Health Sciences Campus, B.S. Miller Hall, Athens, GA, 30602, USA, willahe@uga.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 0340-0131 ISBN Medium
Area Expedition Conference
Notes PMID:25261318 Approved no
Call Number IDA @ john @ Serial 1064
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