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Author Stevens, R.G.
Title (down) Light-at-night, circadian disruption and breast cancer: assessment of existing evidence Type Journal Article
Year 2009 Publication International Journal of Epidemiology Abbreviated Journal Int J Epidemiol
Volume 38 Issue 4 Pages 963-970
Keywords Human Health; Animals; Blindness/complications/epidemiology; Breast Neoplasms/epidemiology/*etiology/metabolism; Chronobiology Disorders/*complications/epidemiology/metabolism; Circadian Rhythm/physiology; Disease Models, Animal; Female; Humans; Light Signal Transduction/physiology; Lighting/adverse effects; Melatonin/biosynthesis; Sleep/physiology; Time Factors; *Work Schedule Tolerance
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.
Address Department of Community Medicine, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-6325, USA. bugs@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 0300-5771 ISBN Medium
Area Expedition Conference
Notes PMID:19380369; PMCID:PMC2734067 Approved no
Call Number LoNNe @ christopher.kyba @ Serial 527
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Author Wood, B.; Rea, M.S.; Plitnick, B.; Figueiro, M.G.
Title (down) Light level and duration of exposure determine the impact of self-luminous tablets on melatonin suppression Type Journal Article
Year 2013 Publication Applied Ergonomics Abbreviated Journal Appl Ergon
Volume 44 Issue 2 Pages 237-240
Keywords Adolescent; *Computers, Handheld; Female; Humans; Light/*adverse effects; Male; Melatonin/*biosynthesis; Photoperiod; Saliva/*metabolism; Sleep/radiation effects; Time Factors; Young Adult; melatonin
Abstract Exposure to light from self-luminous displays may be linked to increased risk for sleep disorders because these devices emit optical radiation at short wavelengths, close to the peak sensitivity of melatonin suppression. Thirteen participants experienced three experimental conditions in a within-subjects design to investigate the impact of self-luminous tablet displays on nocturnal melatonin suppression: 1) tablets-only set to the highest brightness, 2) tablets viewed through clear-lens goggles equipped with blue light-emitting diodes that provided 40 lux of 470-nm light at the cornea, and 3) tablets viewed through orange-tinted glasses (dark control; optical radiation <525 nm approximately 0). Melatonin suppressions after 1-h and 2-h exposures to tablets viewed with the blue light were significantly greater than zero. Suppression levels after 1-h exposure to the tablets-only were not statistically different than zero; however, this difference reached significance after 2 h. Based on these results, display manufacturers can determine how their products will affect melatonin levels and use model predictions to tune the spectral power distribution of self-luminous devices to increase or to decrease stimulation to the circadian system.
Address Lighting Research Center, Rensselaer Polytechnic Institute, 21 Union Street, Troy, NY 12180, USA. woodb5@rpi.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 0003-6870 ISBN Medium
Area Expedition Conference
Notes PMID:22850476 Approved no
Call Number IDA @ john @ Serial 136
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Author Fonken, L.K.; Workman, J.L.; Walton, J.C.; Weil, Z.M.; Morris, J.S.; Haim, A.; Nelson, R.J.
Title (down) Light at night increases body mass by shifting the time of food intake Type Journal Article
Year 2010 Publication Proceedings of the National Academy of Sciences of the United States of America Abbreviated Journal Proc Natl Acad Sci U S A
Volume 107 Issue 43 Pages 18664-18669
Keywords Animals; Body Mass Index; *Circadian Rhythm; Disease Models, Animal; Eating/*physiology/psychology/*radiation effects; Energy Intake; Feeding Behavior/physiology/psychology/radiation effects; Glucose Tolerance Test; Humans; Male; Metabolic Syndrome X/etiology; Mice; Motor Activity; Obesity/*etiology/pathology/physiopathology/psychology; *Photoperiod
Abstract The global increase in the prevalence of obesity and metabolic disorders coincides with the increase of exposure to light at night (LAN) and shift work. Circadian regulation of energy homeostasis is controlled by an endogenous biological clock that is synchronized by light information. To promote optimal adaptive functioning, the circadian clock prepares individuals for predictable events such as food availability and sleep, and disruption of clock function causes circadian and metabolic disturbances. To determine whether a causal relationship exists between nighttime light exposure and obesity, we examined the effects of LAN on body mass in male mice. Mice housed in either bright (LL) or dim (DM) LAN have significantly increased body mass and reduced glucose tolerance compared with mice in a standard (LD) light/dark cycle, despite equivalent levels of caloric intake and total daily activity output. Furthermore, the timing of food consumption by DM and LL mice differs from that in LD mice. Nocturnal rodents typically eat substantially more food at night; however, DM mice consume 55.5% of their food during the light phase, as compared with 36.5% in LD mice. Restricting food consumption to the active phase in DM mice prevents body mass gain. These results suggest that low levels of light at night disrupt the timing of food intake and other metabolic signals, leading to excess weight gain. These data are relevant to the coincidence between increasing use of light at night and obesity in humans.
Address Department of Neuroscience, Ohio State University, Columbus, OH 43210, USA. fonken.1@osu.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 0027-8424 ISBN Medium
Area Expedition Conference
Notes PMID:20937863; PMCID:PMC2972983 Approved no
Call Number IDA @ john @ Serial 169
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Author Kloog, I.; Haim, A.; Stevens, R.G.; Barchana, M.; Portnov, B.A.
Title (down) Light at night co-distributes with incident breast but not lung cancer in the female population of Israel Type Journal Article
Year 2008 Publication Chronobiology International Abbreviated Journal Chronobiol Int
Volume 25 Issue 1 Pages 65-81
Keywords Human Health; Breast Neoplasms/*epidemiology/etiology; Female; Humans; Israel/epidemiology; *Light; Lung Neoplasms/epidemiology; Multivariate Analysis; Risk Factors
Abstract Recent studies of shift-working women have reported that excessive exposure to light at night (LAN) may be a risk factor for breast cancer. However, no studies have yet attempted to examine the co-distribution of LAN and breast cancer incidence on a population level with the goal to assess the coherence of these earlier findings with population trends. Coherence is one of Hill's “criteria” (actually, viewpoints) for an inference of causality. Nighttime satellite images were used to estimate LAN levels in 147 communities in Israel. Multiple regression analysis was performed to investigate the association between LAN and breast cancer incidence rates and, as a test of the specificity of our method, lung cancer incidence rates in women across localities under the prediction of a link with breast cancer but not lung cancer. After adjusting for several variables available on a population level, such as ethnic makeup, birth rate, population density, and local income level, a strong positive association between LAN intensity and breast cancer rate was revealed (p<0.05), and this association strengthened (p<0.01) when only statistically significant factors were filtered out by stepwise regression analysis. Concurrently, no association was found between LAN intensity and lung cancer rate. These results provide coherence of the previously reported case-control and cohort studies with the co-distribution of LAN and breast cancer on a population basis. The analysis yielded an estimated 73% higher breast cancer incidence in the highest LAN exposed communities compared to the lowest LAN exposed communities.
Address Department of Natural Resources & Environmental Management, University of Haifa, Haifa, Israel
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 0742-0528 ISBN Medium
Area Expedition Conference
Notes PMID:18293150 Approved no
Call Number LoNNe @ christopher.kyba @ Serial 528
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Author Li, Q.; Zheng, T.; Holford, T.R.; Boyle, P.; Zhang, Y.; Dai, M.
Title (down) Light at night and breast cancer risk: results from a population-based case-control study in Connecticut, USA Type Journal Article
Year 2010 Publication Cancer Causes & Control : CCC Abbreviated Journal Cancer Causes Control
Volume 21 Issue 12 Pages 2281-2285
Keywords Adult; Aged; Aged, 80 and over; Breast Neoplasms/epidemiology/*etiology; Carcinoma/epidemiology/*etiology; Case-Control Studies; Circadian Rhythm/physiology; Connecticut/epidemiology; Female; Humans; *Light/adverse effects; Middle Aged; Population; Questionnaires; Risk Factors; United States/epidemiology; Work Schedule Tolerance/physiology; Oncogenesis
Abstract OBJECTIVE: To investigate the potential association between domestic exposure to light at night (LAN) and the risk of human breast cancer. METHODS: A case-control study of female breast cancer was conducted in Connecticut. A total of 363 incident breast cancer cases and 356 age frequency-matched controls were interviewed using a standardized, structured questionnaire to obtain information on sleeping patterns and bedroom light environment. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by unconditional multivariate logistic regression. RESULTS: A non-significantly increased risk of breast cancer was observed among postmenopausal women for those keeping lights on while sleeping (OR = 1.4, 95% CI 0.7, 2.7), those who reported mainly sleeping in the daytime (OR = 1.4, 95% CI 0.5, 4.3), and those not drawing the curtains/window shades while sleeping at night (OR = 1.2, 95% CI 0.8, 1.9). CONCLUSION: The results from this study suggest a potential increased risk of breast cancer associated with domestic exposure to LAN. Further studies with larger sample size are needed to confirm the results.
Address Department of Social Medicine, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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:20927578; PMCID:PMC3154700 Approved no
Call Number IDA @ john @ Serial 161
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