A Validation Study of Satellite-based Measure of Artificial Light at Night for its Application in Epidemiological Research

PROJECT SUMMARY Artificial light at night (ALAN) is an emerging environmental. Growing research has linked higher ALAN exposures to a broad range of diseases, including cardiometabolic conditions. To date, the vast majority of epidemiological studies on health effects of ALAN relied on satellite data to measure ALAN. Although satellite

data are publicly available and provide estimates across wide geographic areas and large populations, it remains unknown to what degree satellite-based measures reflect individual-level exposures. To the best of our knowledge, only two published studies compared satellite-based with individual-level ALAN measures and

reported weak or no correlation between the two. However, these studies have several limitations: First, previous studies had small sample sizes with low ALAN levels, which limited statistical power and generalizability. Second, previous studies lacked diversities required for in-depth analysis in subpopulations with different

geographic, demographic, socioeconomic and lifestyle characteristics, all of which may influence how well satellite data capture individual-level exposures. Third, none of the previous studies investigated the validity of satellite data in the context of studying exposure-outcome associations in epidemiological research. We propose

to conduct a comprehensive validation study of satellite-based ALAN measure in a large, diverse and nationally representative sample, the National Health and Nutrition Examination Survey (NHANES, 2011-2014). The NHANES collected individual-level ALAN measures using wrist monitors and residential addresses that can be

linked to satellite data, as well as information on a wide range of health outcomes, including cardiometabolic markers that have been consistently linked to ALAN. Aim 1. Compare satellite-based ALAN measures with individual-level measures in the overall sample. Aim 2 Compare satellite-based ALAN measures with individual-

level measures in subgroups with different sociodemographic, lifestyle and geographic characteristics. Aim 3 Compare the associations between cardiometabolic outcomes and ALAN using satellite-based or individual-level measures. In the past years, we have worked diligently to obtain approval from the National Center for Health

Statistics to access the restricted address data, acquired and linked satellite data to NHANES, and determined the relevant individual-level ALAN measures for comparison with satellite measures. With focused aims to address gaps in existing research, our study will be the first large-scale validation study of satellite-based

ALAN measures in a nationally representative and diverse dataset with relevant health outcomes. It is innovative because it will not only provide an overall measure of validity but will also examine whether and how satellite data validity is influenced by population characteristics, and answer the critical question regarding the

utility of satellite data in assessing ALAN-health associations in epidemiological research. Thus, our study is significant because it will provide key information for better interpreting existing epidemiological evidence, guiding the design of future studies, and enhancing the translational value of ALAN research.