Light at night and cause-specific mortality risk in Mainland China: a nationwide observational study

Identification of preventive biomarkers associated with circadian rhythms in traumatic brain injury-mediated depression: Expression of SERPINE1 protein and bioinformatics analysis

Traumatic brain injury (TBI) represents the leading cause of trauma-related mortality, with depression being the most common psychiatric condition following TBI. Although disruptions in circadian rhythms and clock genes have been linked to both conditions, their precise regulatory mechanisms remain unclear. Identifying circadian rhythm-related genes is critical for the prevention and diagnosis of TBI and depression. This study employs Mendelian Randomization (MR) analysis to establish a positive correlation between TBI and depression. Using Weighted Gene Co-expression Network Analysis (WGCNA) on Gene Expression Omnibus (GEO) datasets derived from TBI and depression tissue samples, we identified 99 shared genes functionally linked to circadian rhythms. Furthermore, machine learning algorithms and Receiver Operating Characteristic (ROC) curve analysis identified SERPINE1 as a key diagnostic biomarker for both TBI and depression. In vivo and in vitro experiments further demonstrated that TBI often triggers the development of depression. Suppressing SERPINE1 expression reduced Claudin-1 and BDNF protein levels, alleviating TBI and depressive symptoms. Our findings indicate that SERPINE1 overexpression, which is positively correlated with neutrophil levels, may increase the risk of depression following TBI by disrupting circadian rhythms. This positions SERPINE1 as a critical predictive and diagnostic biomarker for TBI-mediated depression.

Outdoor artificial light-at-night and cardiometabolic disease risk: an urban perspective from the Catalan GCAT cohort study

We investigated the association between outdoor artificial light-at-night (ALAN) exposure and cardiometabolic risk in the GCAT study. We included 9752 participants from Barcelona (59% women) and used satellite images (30 m resolution) and estimated photopic illuminance and the circadian regulation-relevant melanopic equivalent daylight illuminance (melanopic EDI). We explored the association between ALAN exposure and prevalent obesity, hypertension, and diabetes with logistic regressions and assessed the relationship with incident cardiometabolic diseases ascertained through electronic health records (mean follow-up 6.5 years) with Cox proportional hazards regressions. We observed an association between photopic illuminance and melanopic EDI and prevalent hypertension, odds ratio (OR) = 1.09 (95% CI, 1.01-1.16) and 1.08 (1.01-1.14) per interquartile range increase (0.59 and 0.16 lux, respectively). Both ALAN indicators were linked to incident obesity (hazard ratio [HR] = 1.29, 1.11-1.48 and 1.19, 1.05-1.34) and hemorrhagic stroke (HR = 1.73, 1.00-3.02 and 1.51, 0.99-2.29). Photopic illuminance was associated with incident hypercholesterolemia in all participants (HR = 1.17, 1.05-1.31) and with angina pectoris only in women (HR = 1.55, 1.03-2.33). Further research in this area and increased awareness on the health impacts of light pollution are needed. Results should be interpreted carefully since satellite-based ALAN data do not estimate total individual exposure. This article is part of a Special Collection on Environmental Epidemiology.

Association between outdoor light at night exposure and preterm birth and effect modification by pre-pregnancy stress: A national population-based retrospective cohort study

BACKGROUND

Whether pre-pregnancy stress could modify the effects of outdoor artificial light at night (ALAN) on preterm birth (PB) has been unknown. This study aimed to explore the association between outdoor ALAN exposure and the risk of PB, as well as the effect modification by pre-pregnancy stress.

METHODS

This national population-based retrospective cohort study included women of reproductive age (21-49 years) from the National Free Preconception Health Examination Project (NPHCP) across 220 counties in China, from 2010 to 2012. ALAN exposure was quantified using satellite data, and pre-pregnancy stress was assessed via a structured questionnaire focusing on life, friend, economic, and total stress. The primary outcomes were PB (28-37 weeks) and extremely PB (<28 weeks). Logistic regression models were used to estimate the risk odd ratios (ORs) of PB along with per interquartile range (IQR) increase in ALAN exposure, as well as the potential effect modification by pre-pregnancy stress. Stratified analysis was also conducted to explore differences across socioeconomic status.

RESULTS

A total of 549,654 pregnant women were participated in this study. An IQR (8.0 nW/cm2/sr) increase in 1-year average ALAN exposure was associated with ORs of 1.08 (95 %CI: 1.03-1.13) and 1.03 (95 %CI: 1.02-1.04) for extremely PB and PB, respectively. Higher pre-pregnancy life stress levels were associated with a stronger association between outdoor ALAN exposure (1-year average) and extremely PB, with an odds ratio of 1.04 (95 % CI: 0.97-1.10) in the lower group and 1.16 (95 % CI: 1.08-1.24) in the higher group (P for difference = 0.017). Higher total, life, economic, and friend pre-pregnancy stress may amplify the effect of ALAN on PB risk. For instance, an IQR increment in ALAN exposure was associated with ORs of 1.02 (95 % CI: 1.00, 1.03) and 1.07 (95 % CI: 1.05, 1.10) among participants with low and high total stress (P for difference <0.001). Stratified analyses indicated more apparent effect modifications by pre-pregnancy stress in participants with lower educational levels, with non-farmer occupation, living in rural areas, and living in south regions.

CONCLUSIONS

Our findings suggest that higher pre-pregnancy stress levels may amplify the risk of PB associated with outdoor ALAN exposure, especially among women with lower educational levels, of non-farmer occupation, and living in rural areas or in south regions.

Outdoor light at night exposure was associated with hypothyroidism in pregnant women: A national study in China

BACKGROUND

Evidence on the influence of outdoor artificial light at night (ALAN) on hypothyroidism in pregnant women is scarce. We aimed to investigate the association between outdoor ALAN exposure and hypothyroidism in pregnancy.

METHODS

81,820 pregnant women from the China Birth Cohort Study (CBCS) were analyzed, which recruited from 18 provinces and autonomous regions in China between February 2018 and December 2020. Hypothyroidism was defined based on clinical diagnosis by physicians. Outdoor ALAN exposure (nW/cm2/sr) within 1500 m was estimated using VIIRS/DNB satellite data based on the participants' residential address. The Outdoor ALAN was divided in quartiles, with the lowest quartile (Q1) serving as the reference group. Generalized linear mixed models were employed to estimate the association between ALAN exposure and hypothyroidism.

RESULTS

Among the 81,120 pregnant women, 3902 (4.77 %) were diagnosed hypothyroidism. Pregnant women with hypothyroidism had significantly higher median (IQR, interquartile range) outdoor ALAN levels during pregnancy compared to those without hypothyroidism (30.97 (18.15) vs. 29.14 (20.21) nW/cm2/sr, p < 0.01). After adjusting for covariates, we found that each quartile increment of outdoor ALAN exposure was associated with an adjusted Odds Ratio (aOR of 1.15 (95 % Confidence Interval [95 % CI]: 1.03-1.27), 1.15 (1.05-1.28), and 1.12 (1.00-1.25) for hypothyroidism, respectively from Q2 to Q4. Additionally, stratified analyses revealed that pre-pregnancy BMI was a significant modifier in the association between outdoor ALAN and hypothyroidism in pregnancy, with stronger effects observed among those who were overweight before pregnancy (1.21 [95 % CI, 1.05-1.39] vs. 1.03 [95 % CI, 0.97-1.10], p for interaction = 0.01).

CONCLUSIONS

Outdoor ALAN exposure is positively associated with hypothyroidism in pregnancy. To benefit maternal and infant health and well-being, recommendations for mitigating ALAN pollution and effective measures to avoid excessive light exposure should be developed.

Identifying the healthy places to live in Australia with a new environmental quality health index

BACKGROUND

Existing environmental quality indices often fail to account for the varying health impacts of different exposures and exclude socio-economic status indicators (SES).

OBJECTIVES

To develop and validate a comprehensive Environmental Quality Health Index (EQHI) that integrates multiple environmental exposures and SES to assess mortality risks across Australia.

METHODS

We combined all-cause, cardiovascular, and respiratory mortality data (2016-2019) from 2,180 Statistical Areas Level 2 with annual mean values of 12 environmental exposures, including PM2.5, ozone, temperature, humidity, normalized difference vegetation index, night light, road and building density, and socioeconomic status. Exposure-mortality relationships were estimated using a spatial age-period-cohort model, and EQHIs (scored 0-100, with higher values indicating better conditions) were constructed. Validation was performed using K-fold cross-validation and spatial regression models.

RESULTS

Validation showed strong model performance (R-squared = 83.53 %, 75.55 %, and 52.44 % for EQHI-all cause, EQHI-CVD, and EQHI-Resp). Each interquartile increase in EQHI-all cause reduced all-cause mortality risk by 10 %, with similar reductions for cardiovascular and respiratory mortality. Geographically, EQHIs were higher in south, east, and southeast coastal regions. From 2016 to 2019, SA2s with the highest EQHI (>75) decreased from 27.1 % to 21.1 %. The population weighted EQHI was highest in Hobart and lowest in Darwin.

CONCLUSIONS

We established, to our knowledge, the first tool to quantify and communicate environmental health risks using three types of mortality data and 12 environmental factors. This EQHI provides a robust framework to assess environmental health risks and guide targeted interventions. Our methodology can be adapted globally to standardize risk evaluation.

Association of regular health check-ups with a reduction in mortality in 625,279 elderly participants with hypertension: A population-based cohort study

OBJECTIVES

Health check-ups constitute an essential part of China's primary health care policy and a key measure for health screening and risk assessment for elderly people with hypertension and chronic diseases. The role of health check-ups in reducing the incidence of cardiovascular and all-cause mortality remains controversial. This study aimed to investigate the relationship between health check-ups and cardiovascular and all-cause mortality in elderly individuals with hypertension.

STUDY DESIGN

Retrospective cohort study.

METHODS

This study included 625,279 elderly participants with hypertension. Associations of regular and irregular health check-ups with cardiovascular disease related (CVD-related) mortality, all-cause mortality and non-CVD-related mortality were tested via the inverse probability of treatment weighting (IPTW) matching and Cox proportional hazard models. Adjusted hazard ratios (HRs) and 95 % confidence intervals (CIs) were estimated for mortality.

RESULTS

A total of 625,279 participants completed health assessments. During a median follow-up of 5.43 years, 45,927 CVD-related deaths and 25,519 non-CVD-related deaths were recorded. After IPTW, regular health check-ups were significantly associated with reduced CVD-related mortality and all-cause mortality (HR: 0.442, 95 % CI: 0.434-0.450; and HR: 0.441, 95 % CI: 0.435-0.448, respectively). An even stronger association between regular health check-ups and reduced CVD-related mortality was observed in participants with diabetes (HR: 0.40, 95 % CI: 0.39-0.42, P for interaction <0.001), dyslipidaemia (HR: 0.43, 95 % CI: 0.42-0.44, P for interaction <0.001) and a high risk or very high risk of hypertension (HR: 0.41, 95 % CI: 0.40-0.42, P for interaction <0.001).

CONCLUSIONS

Regular health check-ups may be associated with reductions in CVD mortality and all-cause mortality in the elderly population with hypertension, especially in individuals with diabetes, dyslipidaemia and a high risk or very high risk of hypertension.

Brighter nights and darker days predict higher mortality risk: A prospective analysis of personal light exposure in >88,000 individuals

Light enhances or disrupts circadian rhythms, depending on the timing of exposure. Circadian disruption contributes to poor health outcomes that increase mortality risk. Whether personal light exposure predicts mortality risk has not been established. We therefore investigated whether personal day and night light, and light patterns that disrupt circadian rhythms, predicted mortality risk. UK Biobank participants (N = 88,905, 62.4 ± 7.8 y, 57% female) wore light sensors for 1 wk. Day and night light exposures were defined by factor analysis of 24-h light profiles. A computational model of the human circadian pacemaker was applied to model circadian amplitude and phase from light data. Cause-specific mortality was recorded in 3,750 participants across a mean (±SD) follow-up period of 8.0 ± 1.0 y. Individuals with brighter day light had incrementally lower all-cause mortality risk (adjusted-HR ranges: 0.84 to 0.90 [50 to 70th light exposure percentiles], 0.74 to 0.84 [70 to 90th], and 0.66 to 0.83 [90 to 100th]), and those with brighter night light had incrementally higher all-cause mortality risk (aHR ranges: 1.15 to 1.18 [70 to 90th], and 1.21 to 1.34 [90 to 100th]), compared to individuals in darker environments (0 to 50th percentiles). Individuals with lower circadian amplitude (aHR range: 0.90 to 0.96 per SD), earlier circadian phase (aHR range: 1.16 to 1.30), or later circadian phase (aHR range: 1.13 to 1.20) had higher all-cause mortality risks. Day light, night light, and circadian amplitude predicted cardiometabolic mortality, with larger hazard ratios than for mortality by other causes. Findings were robust to adjustment for age, sex, ethnicity, photoperiod, and sociodemographic and lifestyle factors. Minimizing night light, maximizing day light, and keeping regular light-dark patterns that enhance circadian rhythms may promote cardiometabolic health and longevity.

Exposure to real-ambient bedroom light at night delayed circadian rhythm in healthy Chinese young adults: A cross-sectional study

BACKGROUND

Light at night (LAN) have attracted increased research attention on account of its widespread health hazards. However, the underlying mechanism remains unknown. The objective of this study was to investigate the effects of real-ambient bedroom LAN exposure on circadian rhythm among young adults and potential sex differences.

METHODS

Bedroom LAN exposure was measured at 60-s intervals for 2 consecutive days using a portable illuminance meter. Circadian phase was determined by the dim light melatonin onset (DLMO) time in 7 time-series saliva samples.

RESULTS

The mean age of the 142 participants was 20.7 ± 0.8 years, and 59.9% were women. The average DLMO time was 21:00 ± 1:11 h, with men (21:19 ± 1:12 h) later than women (20:48 ± 1:07 h). Higher level of LAN intensity (LANavg ≥ 3lx vs. LANavg < 3lx) was associated with an 81.0-min later in DLMO time (95% CI: 0.99, 1.72), and longer duration of nighttime light intensity ≥ 5lx (LAN5; LAN5 ≥ 45 min vs. LAN5 < 45 min) was associated with a 51.6-min later in DLMO time (95% CI: 0.46, 1.26). In addition, the delayed effect of LAN exposure on circadian phase was more pronounced in men than in women (all P-values <0.05).

CONCLUSIONS

Overall, bedroom LAN exposure was significantly associated with delayed circadian rhythm. Additionally, the delayed effect is more significant in men. Keeping bedroom dark at night may be a practicable option to prevent circadian disruption and associated health implications. Future studies with more advanced light measurement instrument and consensus methodology for DLMO assessment are warranted.

Water, Soil, Noise, and Light Pollution: JACC Focus Seminar, Part 2

Various forms of pollution carry a substantial burden with respect to increasing the risk of causing and exacerbating noncommunicable diseases, especially cardiovascular disease. The first part of this 2-part series on pollution and cardiovascular disease provided an overview of the impact of global warming and air pollution. This second paper provides an overview of the impact of water, soil, noise, and light pollution on the cardiovascular system. This review discusses the biological mechanisms underlying these effects and potential environmental biometrics of exposure. What is clear from both these pollution papers is that significant efforts and redoubled urgency are needed to reduce the sources of pollution in our environment, to incorporate environmental risk factors into medical education, to provide resources for research, and, ultimately, to protect those who are particularly vulnerable and susceptible.

Nighttime Outdoor Artificial Light and Risk of Age-Related Macular Degeneration

Importance

Light pollution's impact on human health is increasingly recognized, but its link to exudative age-related macular degeneration (EAMD) remains unclear.

Objective

To investigate the association between exposure to outdoor artificial light at night (OALAN) and the risk of incident EAMD.

Design, Setting, and Participants

In this nationwide population-based case-control study, all individuals 50 years or older with newly diagnosed EAMD between January 1, 2010, and December 31, 2011, were identified with reference to the Korean National Health Insurance Service registration program database for rare and intractable diseases. Birth year- and sex-matched controls (with no EAMD diagnosis until 2020) were selected at a 1:30 ratio. Data were acquired from May 1 to December 31, 2021, and analyzed from June 1 to November 30, 2022.

Exposures

Mean levels of OALAN at participants' residential addresses during 2008 and 2009 were estimated using time-varying satellite data for a composite view of persistent nighttime illumination at an approximate scale of 1 km2.

Main Outcomes and Measures

The hazard ratios (HRs) and 95% CIs of the association between residential OALAN and risk of incident EAMD were determined based on maximum likelihood estimation after adjusting for sociodemographic characteristics, comorbidities, and area-level risk factors (ie, nighttime traffic noise and particulate matter of aerodynamic diameter ≤10 μm in each participant's administrative district of residence).

Results

A total of 126 418 participants were included in the analysis (mean [SD] age, 66.0 [7.9] years; 78 244 men [61.9%]). Of these, 4078 were patients with newly diagnosed EAMD and 122 340 were EAMD-free matched controls. In fully adjusted models, an IQR (55.8 nW/cm2/sr) increase in OALAN level was associated with an HR of 1.67 (95% CI, 1.56-1.78) for incident EAMD. The exposure-response curve demonstrated a nonlinear, concave upward slope becoming more pronounced at higher levels of light exposure (ie, at approximately 110 nW/cm2/sr). In a subgroup analysis, an IQR increase in OALAN was associated with increased risk of incident EAMD in urban areas (HR, 1.46 [95% CI, 1.33-1.61]) but not in rural areas (HR, 1.01 [95% CI, 0.84-1.22]).

Conclusions and Relevance

In this nationwide population-based case-control study, higher levels of residential OALAN were associated with an increased risk of incident EAMD. Future studies with more detailed information on exposure, individual adaptive behaviors, and potential mediators are warranted.

Artificial light at night and risk of depression: a systematic review and meta-analysis

BACKGROUND

Artificial light at night (ALAN) has been increasingly recognized as a potential environmental risk factor for mental health issues. However, no meta-analyses have been conducted to summarize the findings. This study aimed to evaluate the pooled associations between outdoor and indoor ALAN exposures and the risk of depression.

METHODS

Adhering to the PRISMA guideline, we conducted systematic searches across PubMed, Web of Science, EMBASE, Cochrane, and Ovid databases for studies published before May 1st, 2024.

RESULTS

A total of 7 studies (5 for outdoor ALAN and 2 for indoor ALAN) with a combined total of 560,219 participants were included in the meta-analysis. Specifically, a 1 nW/cm2/sr increase in outdoor ALAN was associated with a 0.43% (95% CI: 0.21%, 0.65%) increase in depression risk. Meanwhile, a 1 lux increase in indoor ALAN was associated with a 3.29% (95% CI: 0.85%, 5.79%) increase in depression risk. No potential heterogeneity was observed for outdoor ALAN exposure and indoor ALAN exposure. Subgroup analyses for outdoor ALAN indicated that development level, sample size, age group, sex, study design, modality of depression assessment, or adjustment of sleep-related variables in models may not be potential sources of heterogeneity. Sensitivity analyses confirmed the robustness of the findings, while evidence of publication bias was observed for studies on outdoor ALAN.

CONCLUSIONS

Our findings suggest that both outdoor and indoor ALAN exposures are associated with increased risk of depression. These results underscore the importance of considering outdoor and indoor ALAN in public health strategies aimed at reducing depression risk. Nevertheless, further studies with prospective design are still warranted considering the limited study numbers.

Association between exposure to outdoor artificial light at night and the risk of preterm birth

Background

This study aimed to investigate the association between outdoor artificial light at night (ALAN) exposure during pregnancy and the risk of preterm birth (PTB).

Methods

A retrospective case-control study was conducted, and data were collected from pregnant women residing in Beijing, China. The level of ALAN exposure during pregnancy was estimated using remote sensing satellite data. Propensity score matching was utilized to match the control group. Logistic and multivariate linear regression were used to analyze the association between ALAN and the risk of PTB. The odds ratio (OR) and partial regression coefficient (β) with 95% confidence interval (CI) were utilized to assess the association.

Results

A total of 2,850 pregnant women were enrolled in this study. ALAN (nW/cm2/sr) exposure was higher in the PTB group than in the control group during first trimester (mean ± standard deviation: 25.30 ± 17.91 vs. 17.56 ± 14.74, p < 0.001) and second trimester (27.07 ± 18.10 vs. 21.93 ± 16.08, p < 0.001). A negative association was found between ALAN exposure and gestation day in the first (β = -0.151, 95%CI: -0.217 to -0.085, p < 0.001) and second trimesters (β = -0.077, 95%CI: -0.139 to -0.015, p = 0.015). ALAN was identified as a risk factor for PTB during the first trimester (OR = 1.032, 95%CI: 1.025-1.040, p < 0.001) and the second trimester (OR = 1.018, 95%CI: 1.011-1.025, p < 0.001), while no significant association was observed in the third trimester.

Conclusion

Our study suggesting that exposure to outdoor ALAN, especially during first and second trimester, was associated with the risk of PTB. These findings highlight the potential impact of ALAN on pregnancy health and offer new insights into the risk of PTB.

Outdoor artificial light at night and risk of early-onset dementia: A case-control study in the Modena population, Northern Italy

Background

Dementia is a neurological syndrome characterized by severe cognitive impairment with functional impact on everyday life. It can be classified as young onset dementia (EOD) in case of symptom onset before 65, and late onset dementia (LOD). The purpose of this study is to assess the risk of dementia due to light pollution, and specifically outdoor artificial light at night (LAN).

Methods

Using a case-control design, we enrolled dementia patients newly-diagnosed in the province of Modena in the period 2017-2019 and a referent population from their caregivers. We geo-referenced the address of residence on the date of recruitment, provided it was stable for the previous five years. We assessed LAN exposure through 2015 nighttime luminance satellite images from the Visible Infrared Imaging Radiometer Suite (VIIRS). Using a logistic regression model adjusted for age, sex, and education, we calculated the risk of dementia associated with increasing LAN exposure, namely using <10 nW/cm²/sr as reference and considering ≥10-<40 nW/cm²/sr intermediate and ≥40 nW/cm²/sr high exposure, respectively We also implemented non-linear assessment using a spline regression model.

Results

We recruited 58 EOD cases, 34 LOD cases and 54 controls. Average LAN exposure levels overlapped for EOD cases and controls, while LOD cases showed higher levels. Compared with the lowest exposure, the risk of EOD associated with LAN was higher in the intermediate exposure (OR = 1.36, 95% CI 0.54-3.39), but not in the high exposure category (OR = 1.04, 95% CI 0.32-3.34). In contrast, the risk of LOD was positively associated with LAN exposure, with ORs of 2.58 (95% CI 0.26-25.97) and 3.50 (95% CI 0.32-38.87) in the intermediate and high exposure categories, respectively. The spline regression analysis showed substantial lack of association between LAN and EOD, while almost linear although highly imprecise association emerged for LOD.

Conclusions

Although the precision of the estimates was affected by the limited sample size and the study design did not allow us to exclude the presence of residual confounding, these results suggest a possible role of LAN in the etiology of dementia, particularly of its late-onset form.