Artificial light at night disrupts expression of circadian and metabolic genes in the green anole lizard ( Anolis carolinensis )

Artificial light at night (ALAN) disrupts natural light–dark cycles, posing ecological challenges for wildlife in urban environments. This study investigated ALAN’s effects on gene expression in the brain, liver, eyes, gonad and skin of green anole lizards (Anolis carolinensis), increasingly exposed to urban light pollution. We hypothesized that ALAN would alter circadian rhythms by disrupting nighttime darkness and predicted differential expression of genes involved in photoreception, circadian regulation, metabolism and photoperiodic responses. To identify affected pathways, we analysed the expression of circadian and metabolic genes under three conditions: midday in full light, midnight in full darkness and midnight under artificial light. Differential expression analysis revealed that clock-related genes were significantly altered in the brain, liver and skin following ALAN exposure. Genes involved in glucagon signalling and lipid metabolism were differentially expressed in the liver, indicating potential metabolic disruptions. The skin showed distinct responses, with genes related to cellular processes such as wound healing upregulated under natural light–dark conditions, suggesting compromised repair mechanisms under ALAN. Our findings demonstrate that ALAN disrupts core circadian genes and physiological processes, providing the first transcriptomics evidence of light pollution’s impact on green anoles. We also developed an interactive online database for exploring gene expression changes under ALAN.