Shedding Some Light in the Dark—A Comparison of Personal Measurements with Satellite-Based Estimates of Exposure to Light at Night among Children in the Netherlands

Abstract

Background:Exposure to light at night (LAN) can perturb the biological clock and affect sleep and health. Previous epidemiological studies have evaluated LAN levels measured by satellites, but the validity of this measure as a proxy for personal LAN exposure is unclear. In addition, outdoor satellite-measured LAN levels are higher in urban environments, which means that this measure could potentially represent a proxy for other, likely urban, environmental exposures.Objectives:We evaluated correlations of satellite-assessed LAN with measured bedroom light levels and explored correlations with other environmental exposures, in particular, air pollution, green space, and area-level socioeconomic position (SEP).Methods:We compared satellite measurements with evening and nighttime bedroom measurements of illuminance (in units of lux) for 256 children, and we evaluated correlations between satellite-based measures and other urban exposures such as air pollution, area-level SEP, and surrounding green space for 3,021 children.Results:Satellite-measured LAN levels (nanowatts per centimeter squared per steradian) were not correlated with measured evening or nighttime lux levels [Spearman correlation coefficients (rnormalS) −0.11 to 0.04]. There was a weak correlation with measurements during the darkest time period if parents and their children reported that outdoor light sometimes or usually influenced indoor light levels (rnormalS=0.31, n=28). In contrast, satellite-measured LAN levels were correlated with air pollution (rnormalS=0.76 with NO2, rnormalS=0.71 with PM10), and surrounding green space (rnormalS=−0.71 for green space within 1km of the home). A weak correlation with area-level SEP was also observed (rnormalS=0.24).Conclusions:Outdoor satellite-assessed outdoor LAN exposure levels were correlated with urban environmental exposures, but they were not a good proxy for indoor evening or nighttime personal exposure as measured in our study population of 12-y-old children. Studies planning to evaluate potential risks from LAN should consider such modifying factors as curtains and indoor lighting and the use of electronic devices and should include performing indoor or personal measurements to validate any exposure proxies. The moderate-to-strong correlation of outdoor LAN with other environmental exposures should be accounted for in epidemiological investigations. https://doi.org/10.1289/EHP3431

Applications of Satellite Remote Sensing of Nighttime Light Observations: Advances, Challenges, and Perspectives

“…Studies using images with higher resolution and multi-spectral bands taken from the ISS demonstrated that exposure to the blue-light spectrum of outdoor artificial light at night appeared to have stronger effects on hormone-dependent cancer incidence (i.e., prostate and breast cancers) compared to the green-light and red-light spectrums [205,206]. Using VIIRS/DNB images and ISS photos of outdoor light, a comparison of personal measurements with satellite-based estimates of exposure to night light found a discrepancy between outdoor NTL and indoor light exposure [207], indicating that the modifying factors should be used when using the satellite NTL to evaluate potential effects of night light on human health. Such findings can help make better policies for minimizing the adverse health effects of artificial light exposure on human health.…”

Light and Life at Night as Circadian Rhythm Disruptors

“…However, these levels were not correlated with measured bedroom light levels in evening or nighttime [28,29]. And there is only a weak correlation between satellite-measured ALAN and outdoor light levels [28]. These studies suggest that the significant association of ALAN with breast cancer in general population should not be interpreted as a direct ALAN risk in breast cancer.…”

“…These studies all used satellite-measured ALAN levels to determine exposure. However, these levels were not correlated with measured bedroom light levels in evening or nighttime [28,29]. And there is only a weak correlation between satellite-measured ALAN and outdoor light levels [28].…”

“…Several subsequent studies found a significant association between breast cancer and satellite ALAN levels [26,27,86]. However, critical studies have shown that satellite photometry is not correlated with measured bedroom light levels in the evening or night [28,29] and has only a weak correlation with outdoor light levels [28]. Satellite photometry did not provide enough variability to evaluate the association between melatonin and outdoor ALAN levels [87].…”

Constant Light Exerted Detrimental Cardiovascular Effects Through Sympathetic Hyperactivity in Normal and Heart Failure Rats

“…Constant light (CL) was an extremity of prolonged light exposure, which may occur naturally or artificially. Due to light pollution in public and private areas, constant light is a major part of people's lives quietly without attracting notice (Huss et al, 2019;Park et al, 2019). Constant light exposure was able to influence people's behavior and health, making adverse effects on the cardiovascular system reportedly (Furlan et al, 2000;Chang et al, 2015;Reynolds et al, 2017;Benedetto and Contin, 2019;Bohmer et al, 2019).…”