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Nehme, P. A., Amaral, F., Lowden, A., Skene, D. J., Cipolla-Neto, J., & Moreno, C. R. C. (2019). Reduced melatonin synthesis in pregnant night workers: metabolic implications for offspring. Medical Hypotheses, 132, 109353.
Abstract: Several novel animal studies have shown that intrauterine metabolic programming can be modified in the event of reduced melatonin synthesis during pregnancy, leading to glucose intolerance and insulin resistance in the offspring. It is therefore postulated that female night workers when pregnant may expose the offspring to unwanted health threats. This may be explained by the fact that melatonin is essential for regulating energy metabolism and can influence reproductive activity. Moreover, the circadian misalignment caused by shift work affects fertility and the fetus, increasing the risk of miscarriage, premature birth and low birth weight, phenomena observed in night workers. Thus, we hypothesize that light-induced melatonin suppression as a result of night work may alter intrauterine metabolic programming in pregnant women, potentially leading to metabolic disorders in their offspring.
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Xiao, Q., Gee, G., Jones, R. R., Jia, P., James, P., & Hale, L. (2019). Cross-sectional association between outdoor artificial light at night and sleep duration in middle-to-older aged adults: The NIH-AARP Diet and Health Study. Environ Res, 180, 108823.
Abstract: INTRODUCTION: Artificial light at night (ALAN) can disrupt circadian rhythms and cause sleep disturbances. Several previous epidemiological studies have reported an association between higher levels of outdoor ALAN and shorter sleep duration. However, it remains unclear how this association may differ by individual- and neighborhood-level socioeconomic status, and whether ALAN may also be associated with longer sleep duration. METHODS: We assessed the cross-sectional relationship between outdoor ALAN and self-reported sleep duration in 333,365 middle- to older-aged men and women in the NIH-AARP Diet and Health Study. Study participants reported baseline addresses, which were geocoded and linked with outdoor ALAN exposure measured by satellite imagery data obtained from the U.S. Defense Meteorological Satellite Program's Operational Linescan System. We used multinomial logistic regression to estimate the multinomial odds ratio (MOR) and 95% confidence intervals (CI) for the likelihood of reporting very short (<5h), short (<7h) and long (>/=9h) sleep relative to reporting 7-8h of sleep across quintiles of LAN. We also conducted subgroup analyses by individual-level education and census tract-level poverty levels. RESULTS: We found that higher levels of ALAN were associated with both very short and short sleep. When compared to the lowest quintile, the highest quintile of ALAN was associated with 16% and 25% increases in the likelihood of reporting short sleep in women (MORQ1 vs Q5, (95% CI), 1.16 (1.10, 1.22)) and men (1.25 (1.19, 1.31)), respectively. Moreover, we found that higher ALAN was associated with a decrease in the likelihood of reporting long sleep in men (0.79 (0.71, 0.89)). We also found that the associations between ALAN and short sleep were larger in neighborhoods with higher levels of poverty. CONCLUSIONS: The burden of short sleep may be higher among residents in areas with higher levels of outdoor LAN, and this association is likely stronger in poorer neighborhoods. Future studies should investigate the potential benefits of reducing light intensity in high ALAN areas in improve sleep health.
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Zhu, X., Guo, X., Zhang, J., Liu, J., & Jiang, F. (2020). Phosphor-free, color-mixed, and efficient illuminant: Multi-chip packaged LEDs for optimizing blue light hazard and non-visual biological effects. Optics and Lasers in Engineering, 134, 106174.
Abstract: Currently many evaluation models on the photobiological effects (PBE) of light sources do not consider the influence of age and luminance on the pupil diameter, which affects the light radiation intensity on the human retina. In this study, the pupil diameter is taken into consideration when evaluating the PBE of several light sources. Moreover, the correction factor M is proposed. The blue light hazard (BLH) efficacy and the circadian rhythm (CR) effects of the daylight at dusk, together with three indoor light sources with a correlated color temperature (CCT) of about 3000 K were evaluated by using a corrected evaluation model. The results show that an incandescent lamp is more photobiologically friendly for humans, despite being inefficient. Based on high wall-plug efficiency (WPE) GaN-based yellow (565 nm, 24.3%@20 A/cm2) and green (522 nm, 41.3%@20 A/cm2) LEDs on silicon substrate, incandescent-like spectrum and phosphor-free color-mixed white LEDs (CM-LEDs) with a general color rendering index (CRI) of 94, a CCT of 2866 K, and an efficiency of 131 lm/W were manufactured by mixing blue, cyan, green, yellow and red LEDs. The PBE evaluation results of such CM-LEDs are superior to those of an incandescent lamp. Moreover, blue light free and candlelight-toned LEDs with an efficiency of 120.3 lm/W, a general CRI of 84, a special CRI R9 of 93.3, and a CCT of 1810 K were fabricated by mixing yellow and red LEDs (R&Y-mixed LEDs). The R&Y-mixed LEDs show no blue light weighted quantities and have a weaker influence on the CR shift. They are photobiologically friendly for humans and suitable for nocturnal indoor and outdoor lighting environments.
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Obayashi, K., Yamagami, Y., Tatsumi, S., Kurumatani, N., & Saeki, K. (2019). Indoor light pollution and progression of carotid atherosclerosis: A longitudinal study of the HEIJO-KYO cohort. Environment International, 133, 105184.
Abstract: Exposure to light at inappropriate times in relation to the solar cycle can disturb circadian endocrine and metabolic rhythms. Previous studies have suggested an association between light exposure at night (LAN) and obesity, an important risk factor of atherosclerosis, although it remains unclear whether LAN associates with progression of atherosclerosis. To evaluate the longitudinal association between bedroom LAN intensity and progression of carotid atherosclerosis, light intensity in the bedroom at baseline and carotid artery intima-media thickness (IMT) at baseline and follow-up were measured in 989 elderly participants (945 at baseline and 780 at a median follow-up time of 34 months). The mean age of the participants was 71.4 ± 6.9 years. The average mean and maximal carotid IMT at baseline were 0.88 ± 0.15 and 1.10 ± 0.32 mm, respectively. The median intensity of bedroom LAN was 0.68 lx (IQR, 0.07–3.29). In multivariable analysis adjusted for potential confounders, the highest LAN group exhibited a significant increase in mean carotid IMT (adjusted β, 0.028; 95% CI, 0.005–0.052; P = 0.019) compared with the lowest LAN quartile group. A similar relationship was found between LAN and maximal carotid IMT (adjusted β, 0.083; 95% CI, 0.037–0.129; P < 0.001).
In conclusion, we found a clear and significant association between bedroom LAN intensity and progression of subclinical carotid atherosclerosis, which was independent of known risk factors for atherosclerosis, including age, obesity, smoking, economic status, hypertension, and diabetes. Indoor light pollution may be a potential risk factor for atherosclerosis in the general population.
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Zhong, C., Franklin, M., Wiemels, J., McKean-Cowdin, R., Chung, N. T., Benbow, J., et al. (2020). Outdoor artificial light at night and risk of non-Hodgkin lymphoma among women in the California Teachers Study cohort. Cancer Epidemiol, 69, 101811.
Abstract: BACKGROUND: Outdoor artificial light at night (ALAN) has been implicated in a growing number of adverse health outcomes. ALAN is believed to disrupt circadian rhythms and has been associated with increased inflammation, one of the hallmarks of cancer. We examined the association between outdoor ALAN and a cancer strongly associated with autoimmune and inflammatory conditions, non-Hodgkin lymphoma (NHL), in the prospective California Teachers Study cohort. METHODS: Outdoor ALAN was assigned to participant addresses at study baseline (1995-96) through use of the New World Atlas of Artificial Night Sky Brightness. Among 105,937 women followed from 1995 to 2015, linkage to the California Cancer Registry identified 873 incident cases of NHL. Age-stratified Cox proportional hazards models were used to calculate hazard ratios (HR) and 95 % confidence intervals (95 %CI) for overall NHL and the most common NHL subtypes; diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL) and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Multivariate analyses adjusted for previously reported subtype specific covariates (e.g. body mass index (BMI) for DLBCL). RESULTS: Compared to the lowest quintile, participants residing in the highest quintile of outdoor ALAN at baseline were more likely to develop NHL (HR = 1.32, 95 %CI = 1.07-1.63), and, in particular, DLBCL (HR = 1.87, 95 %CI = 1.16-3.02). The elevated risk for DLBCL remained statistically significant after adjusting for age, race/ethnicity, BMI, and socioeconomic status (DLBCL:HR = 1.87, 95 %CI = 1.16-3.02, NHL:HR = 1.32, 95 %CI = 1.07-1.63). There was no association between ALAN and FL or CLL/SLL. CONCLUSION: DLBCL risk was elevated among women residing in neighborhoods with greater outdoor ALAN. Future research in circadian disruption and DLBCL may clarify potential biological processes implicated in this association.
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