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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TL;DR: The present work highlights the history and importance of the relationship between both Melatonin and Melanopsin to maintain a healthy ocular homeostasis and regulates the regulation of intraocular pressure.
Abstract: espanolMelatonina es una neurohormona sintetizada en varias estructuras oculares, aparte de su fuente original, la glandula pineal. Es de gran importancia por varias funciones, como el mantenimiento de valores saludables de presion intraocular. Ademas, disminuye la presion intraocular en el caso de glaucoma. Esta nuerohormona se controla mediante la activacion de un fotopigmento responsable de las tareas no relacionada con la formacion de imagenes en el ojo, este fotopigmento es la Melanopsina, presente en una subclase de celulas ganglionares de la retina y, muy recientemente, se descubrio en diferentes estructuras oculares. Cuando la melanopsina se activa por el componente de longitud de onda corta de la luz, suprime la sintesis de melatonina. Esta accion esta controlada principalmente por la luz que podria afectar varias funciones, incluida la regulacion de la presion intraocular. En este sentido, el presente trabajo destaca la historia y la importancia de la relacion entre la melatonina y la melanopsina para mantener una homeostasis ocular saludable. EnglishMelatonin is a neurohormone synthesized in several ocular structures apart from its original source, the pineal gland. It is of great importance in several functions such as maintaining a healthy values of intraocular pressure. Moreover, it decreases intraocular pressure in the case of glaucoma. This nuerohormone is controlled by the activation of a photopigment responible for non-image forming tasks in the eye, this photopigment is Melanopsin, present in a subclass of retinal ganglion cells, and very recently, it was discovered in different ocular structures. When Melanopsin is activated by the short wavelength component of light, it supresses Melatonin synthesis. This action is controlled mainly by light could affect several functions including the regulation of intraocular pressure. In this sense, the present work highlights the history and importance of the relationship between both Melatonin and Melanopsin to maintain a healthy ocular homeostasis.
5 citations
Cites background from "Light-at-night, circadian disruptio..."
...Light at night is currently associated to several pathologies, and it is considered as a possible risk factor to develop many diseases, starting from obesity to a more serious pathologies such as cancer (56, 57)....
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01 Jan 2019
TL;DR: In this paper, the authors highlight the potential of novel methodologies and data sources to study these landscape qualities, including the use of machine learning for automated image recognition, analysis of social media data (tags, location and image content), as well as citizen science approaches.
Abstract: The need to assess landscape qualities has become increasingly important over the past decades, with landscapes being continuously shaped and re-shaped through dynamic natural and anthropogenic processes. It is now widely recognised that landscapes need to be studied both in terms of their physical and ecological elements as well as how people living in or visiting landscapes perceive and interact with them. Different approaches have been developed over time for assessing these variegated aspects of landscape qualities, which range from methods in the natural sciences to the social sciences and humanities. Using the three examples of wilderness, tranquillity and dark skies as landscape qualities, we review existing quantitative and qualitative approaches to illustrate the potential of interdisciplinary landscape research. Furthermore, we highlight the potential of novel methodologies and data sources to study these landscape qualities, including the use of machine learning for automated image recognition, analysis of social media data (tags, location and image content), as well as citizen science approaches.
5 citations
01 Jan 2019
TL;DR: In this article, the authors present the basic concept of light pollution problematic, and define the biggest light emitters in Vojvodina and surrounding in order to outline the most endangered protected areas by this pollutant.
Abstract: In the last two decades, artificial light at night has increased at alarming rates on global level and numerous negative effects of excessive artificial lighting are characterized as light pollution. However, light pollution has not gained enough attention such as water or air pollution, even though researchers are finding more and more evidence of its adverse impact on the environment. This phenomenon is mostly unknown in Serbia (and wider region), and consequences of light pollution have not yet been assessed. Autonomous Province of Vojvodina has 165 protected areas which cover a surface of approximately 2048 km2 and are home to a large number of strictly protected species. Furthermore, due to its geographical location and characteristics of the relief, Vojvodina is intersected by numerous ecological corridors, especially for avifauna. Likewise, this region is also highly populated and has dense road network which is usually located nearby protected areas. Since artificial lighting is present wherever there are human activities, it can be assumed that protected areas and ecological corridors in Vojvodina Province are endangered with light pollution. The aim of this paper is to present the basic concept of light pollution problematic, and to define the biggest light emitters in Vojvodina and surrounding in order to outline the most endangered protected areas by this pollutant.
5 citations
Cites background from "Light-at-night, circadian disruptio..."
...Melatonin is an oncostatic and anti-carcinogenic agent and at reduced amount of this hormone in the blood, the chances of developing some type of cancer increase (Glickman et al., 2002; Anisimov, 2006; Klog et al., 2008; Stevens, 2009)....
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TL;DR: A systematic review and meta-analysis based on observational studies to examine the association between LAN exposure and sleep problems among human subjects was conducted by as discussed by the authors , where the authors found that individuals with higher levels of LAN exposure were associated with a 22 % (Summary Odds Ratio, SOR: 1.22, 95 %CI: 113-1.33) increased prevalence of sleep problems.
5 citations
TL;DR: The growing contribution of CRDs to the racial disparities associated with the incidence, aggressiveness, and progression of prostate cancer are discussed and the unmet clinical need of integrating circadian-related therapies to enhance current prostate cancer treatment modalities is highlighted.
Abstract: Simple Summary African American (AA) men have 2.4 times higher mortality rate due to prostate cancer than White men in the United States. Evidence implicates circadian rhythm disruption (CRD) as a potential driver of prostate cancer risk and progression. AA men are particularly vulnerable to CRDs due to greater exposure to night shift work, artificial light at night, noise pollution, racial discrimination, and socioeconomic disadvantages. In this review, we discuss the growing contribution of CRDs to the racial disparities associated with the incidence, aggressiveness, and progression of prostate cancer and highlight the unmet clinical need of integrating circadian-related therapies to enhance current prostate cancer treatment modalities. Abstract In the United States, African American (AA) men have a 2.4 times higher mortality rate due to prostate cancer than White men. The multifactorial causes of the racial disparities in prostate cancer involve various social determinants of health, socioeconomic status, and access to healthcare. However, emerging evidence also suggests that circadian rhythm disruption (CRD) contributes to prostate cancer, and AA men may be more susceptible to developing CRDs. Circadian rhythms play a significant role in metabolism, hormone secretion, and sleep/wake cycles. Disruption in these circadian rhythms can be caused by airplane travel/jetlag, night shift work, exposure to light, and neighborhood noise levels, which can contribute to sleep disorders and chronic conditions such as obesity, diabetes, cardiovascular disease, and depression. The drivers of the racial disparities in CRD include night shift work, racial discrimination, elevated stress, and residing in poor neighborhoods characterized by high noise pollution. Given the increased vulnerability of AA men to CRDs, and the role that CRDs play in prostate cancer, elucidating the clock-related prostate cancer pathways and their behavior and environmental covariates may be critical to better understanding and reducing the racial disparities in prostate cancer.
5 citations
References
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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
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
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
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