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Journal ArticleDOI

Light-at-night, circadian disruption and breast cancer: assessment of existing evidence

01 Aug 2009-International Journal of Epidemiology (Oxford University Press)-Vol. 38, Iss: 4, pp 963-970
TL;DR: If a consensus eventually emerges that LAN does increase risk, then the mechanisms for the effect are important to elucidate for intervention and mitigation and will provide for the development of lighting technologies at home and at work that minimize circadian disruption, while maintaining visual efficiency and aesthetics.
Abstract: Background Breast cancer incidence is increasing globally for largely unknown reasons. The possibility that a portion of the breast cancer burden might be explained by the introduction and increasing use of electricity to light the night was suggested >20 years ago. Methods The theory is based on nocturnal light-induced disruption of circadian rhythms, notably reduction of melatonin synthesis. It has formed the basis for a series of predictions including that non-day shift work would increase risk, blind women would be at lower risk, long sleep duration would lower risk and community nighttime light level would co-distribute with breast cancer incidence on the population level. Results Accumulation of epidemiological evidence has accelerated in recent years, reflected in an International Agency for Research on Cancer (IARC) classification of shift work as a probable human carcinogen (2A). There is also a strong rodent model in support of the light-at-night (LAN) idea. Conclusion If a consensus eventually emerges that LAN does increase risk, then the mechanisms for the effect are important to elucidate for intervention and mitigation. The basic understanding of phototransduction for the circadian system, and of the molecular genetics of circadian rhythm generation are both advancing rapidly, and will provide for the development of lighting technologies at home and at work that minimize circadian disruption, while maintaining visual efficiency and aesthetics. In the interim, there are strategies now available to reduce the potential for circadian disruption, which include extending the daily dark period, appreciate nocturnal awakening in the dark, using dim red light for nighttime necessities, and unless recommended by a physician, not taking melatonin tablets.

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Citations
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Journal ArticleDOI
TL;DR: The analysis identified a "halo" geographic pattern of BC incidence, with the highest rates of the disease observed at distances 5-15 km from the state's major cities, and was of high-income communities, with high ALAN located in suburban fringes of thestate's main cities.

8 citations

Journal ArticleDOI
TL;DR: The authors expose le cheminement par lequel nous constituons l'environnement nocturne en objet de recherche interdisciplinaire.

8 citations


Cites background from "Light-at-night, circadian disruptio..."

  • ...On trouve chez Schernhammer et Schulmeister (2004), Megdal et al. (2005), Reiter et al. (2007), Navara et Nelson (2007) et dans les travaux récents de Stevens (2009 ; 2011) des synthèses et des évaluations détaillées des recherches actuelles en la matière....

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Journal ArticleDOI
TL;DR: In this paper, the authors report results of the very first, long-term photometric survey of night sky brightness over Poland's capital, Warsaw, for 636 nights between 2014 and 2016 using a sky quality meter (SQM). Data were collected for all-weather conditions and, for the first time, simultaneously use two independent sources of cloud amount data: surface-based (SYNOP) and satellitebased (Meteosat/SEVIRI).
Abstract: Light pollution is a widely distributed form of anthropogenic pollution that threatens both biodiversity and human health. One of the most popular indicators is known as night sky brightness (NSB), measured with photometric techniques. In the study, we report results of the very first, long-term photometric survey of NSB over Poland's capital, Warsaw, for 636 nights between 2014 and 2016 using a sky quality meter (SQM). Data were collected for all-weather conditions and, for the first time, we simultaneously use two independent sources of cloud amount data: surface-based (SYNOP) and satellite-based (Meteosat/SEVIRI). Results show that Warsaw is significantly polluted by light, with average NSB of 18.65 ± 0.06 magSQM/arcsec2 (15 times higher than unpolluted sky). Zenithal NSB is almost unaffected by moonlight. During astronomical nights, cloud cover was the dominant determinant of NSB, increasing by 7 times for overcast sky. In general, the sky brightened by ∼0.2 magSQM/arcsec2 for each 10% increase in cloud fraction. Satellite-based cloud amount data was found to be a very reliable alternative to traditional SYNOP observations. No statistically significant difference was found for average NSB calculated using satellite and SYNOP datasets. This finding is of particular importance, since the coverage of surface-based data is limited, while satellite observations can be obtained for any location on Earth, and collocate with any NSB photometric station. Our investigation also highlighted that SYNOP data are unreliable when cloud amount is low. This is due to the different fields of view for SQM (20°) and SYNOP (180°) observations of broken cloud.

8 citations

Journal ArticleDOI
TL;DR: The article furthermore discusses the disturbance of sleep patterns caused by electrified environments, and the increasing absence of natural stimuli to the human brain causing chronic 'digital stress' facilitating pathophysiological development.

8 citations

Journal ArticleDOI
TL;DR: A review examines the prognostic value of clock genes in TNBC, and evaluates patterns of clock gene dysregulation in the individual TNBC molecular subtypes.
Abstract: Growing evidence now links circadian disruption (CD) to increased risk of developing multiple types of cancer, including breast cancer (BC). In the US, African-American (AA) BC patients have a higher mortality rate than European-Americans (EAs) with BC, and a prime suspect in this racially disparate burden has been the greater incidence of an aggressive and highly heterogeneous BC subtype called triple-negative BC (TNBC), among AAs. AAs are also more prone to CD as larger proportions of AAs engage in night shift work than EAs, and the chronotype of AAs makes it harder for them to adapt to CD than EAs. Although clock gene dysregulation has been shown to perturb transactivation of key cell cycle and apoptosis regulators, little is known about how clock gene mis-expression affects TNBC outcomes. This review examines the prognostic value of clock genes in TNBC, and evaluates patterns of clock gene dysregulation in the individual TNBC molecular subtypes. Better understanding of how CD contributes to TNBC biology may illuminate new paths to improving disease outcomes and reducing BC-related racial disparities.

8 citations


Cites background from "Light-at-night, circadian disruptio..."

  • ...Conditions which favor melatonin suppression by light during the night, resulting in CD, are known to be a possible cause underlying several health conditions, including hypertension (18), cardiovascular disease (19), and several types of cancer (20), including breast cancer or BC (21,22)....

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References
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Journal ArticleDOI
Hill Ab1
TL;DR: The criteria outlined in "The Environment and Disease: Association or Causation?" help identify the causes of many diseases, including cancers of the reproductive system.
Abstract: In 1965, Austin Bradford Hill published the article "The Environment and Disease: Association or Causation?" in the Proceedings of the Royal Society of Medicine. In the article, Hill describes nine criteria to determine if an environmental factor, especially a condition or hazard in a work environment, causes an illness. The article arose from an inaugural presidential address Hill gave at the 1965 meeting of the Section of Occupational Medicine of the Royal Society of Medicine in London, England. The criteria he established in the article became known as the Bradford Hill criteria and the medical community refers to them when determining whether an environmental condition causes an illness. The criteria outlined in "The Environment and Disease: Association or Causation?" help identify the causes of many diseases, including cancers of the reproductive system.

6,992 citations

Journal Article
TL;DR: This paper contrasts Bradford Hill’s approach with a currently fashionable framework for reasoning about statistical associations – the Common Task Framework – and suggests why following Bradford Hill, 50+ years on, is still extraordinarily reasonable.
Abstract: In 1965, Sir Austin Bradford Hill offered his thoughts on: “What aspects of [an] association should we especially consider before deciding that the most likely interpretation of it is causation?” He proposed nine means for reasoning about the association, which he named as: strength, consistency, specificity, temporality, biological gradient, plausibility, coherence, experiment, and analogy. In this paper, we look at what motivated Bradford Hill to propose we focus on these nine features. We contrast Bradford Hill’s approach with a currently fashionable framework for reasoning about statistical associations – the Common Task Framework. And then suggest why following Bradford Hill, 50+ years on, is still extraordinarily reasonable.

5,542 citations

Journal ArticleDOI
08 Feb 2002-Science
TL;DR: It is shown that retinal ganglion cells innervating the SCN are intrinsically photosensitive, and depolarized in response to light even when all synaptic input from rods and cones was blocked.
Abstract: Light synchronizes mammalian circadian rhythms with environmental time by modulating retinal input to the circadian pacemaker-the suprachiasmatic nucleus (SCN) of the hypothalamus. Such photic entrainment requires neither rods nor cones, the only known retinal photoreceptors. Here, we show that retinal ganglion cells innervating the SCN are intrinsically photosensitive. Unlike other ganglion cells, they depolarized in response to light even when all synaptic input from rods and cones was blocked. The sensitivity, spectral tuning, and slow kinetics of this light response matched those of the photic entrainment mechanism, suggesting that these ganglion cells may be the primary photoreceptors for this system.

3,052 citations

Journal ArticleDOI
12 Dec 1980-Science
TL;DR: Findings establish that the human response to light is qualitatively similar to that of other mammals.
Abstract: Bright artificial light suppressed nocturnal secretion of melatonin in six normal human subjects. Room light of less intensity, which is sufficient to suppress melatonin secretion in other mammals, failed to do so in humans. In contrast to the results of previous experiments in which ordinary room light was used, these findings establish that the human response to light is qualitatively similar to that of other mammals.

1,776 citations

Journal ArticleDOI
TL;DR: The results suggest that, in humans, a single photopigment may be primarily responsible for melatonin suppression, and its peak absorbance appears to be distinct from that of rod and cone cellphotopigments for vision.
Abstract: The photopigment in the human eye that transduces light for circadian and neuroendocrine regulation, is unknown. The aim of this study was to establish an action spectrum for light-induced melatonin suppression that could help elucidate the ocular photoreceptor system for regulating the human pineal gland. Subjects (37 females, 35 males, mean age of 24.5 +/- 0.3 years) were healthy and had normal color vision. Full-field, monochromatic light exposures took place between 2:00 and 3:30 A.M. while subjects' pupils were dilated. Blood samples collected before and after light exposures were quantified for melatonin. Each subject was tested with at least seven different irradiances of one wavelength with a minimum of 1 week between each nighttime exposure. Nighttime melatonin suppression tests (n = 627) were completed with wavelengths from 420 to 600 nm. The data were fit to eight univariant, sigmoidal fluence-response curves (R(2) = 0.81-0.95). The action spectrum constructed from these data fit an opsin template (R(2) = 0.91), which identifies 446-477 nm as the most potent wavelength region providing circadian input for regulating melatonin secretion. The results suggest that, in humans, a single photopigment may be primarily responsible for melatonin suppression, and its peak absorbance appears to be distinct from that of rod and cone cell photopigments for vision. The data also suggest that this new photopigment is retinaldehyde based. These findings suggest that there is a novel opsin photopigment in the human eye that mediates circadian photoreception.

1,708 citations