Telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) are biomarkers of cellular aging influenced by environmental factors. However, evidence linking outdoor artificial light at night (ALAN) to these biomarkers was lacking. This study examined the associations of outdoor ALAN exposure with TL and mtDNAcn in children and adolescents, including potential sex-specific associations. We involved 1151 children and adolescents (ages 6-18) from Liuzhou, China, using a cross-sectional design. Outdoor ALAN exposure was assessed by satellite image data based on the participants' residential addresses. Leukocyte TL and mtDNAcn were measured via the qPCR method. Multiple linear regression models were applied to explore relationships of exposure to outdoor ALAN with TL and mtDNAcn. Each interquartile range (11.46 nW/cm/sr) increment in outdoor ALAN exposure was related to 4.20 % (95 % confidence interval [CI]: -6.38 %, -1.96 %) shorter TL among children and adolescents. The inverse relationship between ALAN exposure and TL was more evident in boys (percent change: -6.38 %, 95 % CI: -9.63 %, -3.02 %) than in girls (percent change: -2.88 %, 95 % CI: -5.80 %, 0.15 %). There was no significant relationship between outdoor ALAN exposure and mtDNAcn. This study suggests an inverse relationship between outdoor ALAN exposure and TL in children and adolescents, particularly in boys. No significant association was found between outdoor ALAN exposure and mtDNAcn. Further research is needed to explore the underlying mechanisms. 2
Circadian Biology