Artificial light at night reshapes diel brain transcriptomics in Dascyllus aruanus damselfish

Here, we examined diel brain transcriptomic alterations in the diurnal damselfish Dascyllus aruanus sampled at both day and night after three nights of ALAN exposure. ALAN partially disrupted circadian rhythmicity, altering diel expression of the core clock regulator bmal1 and glucocorticoid-regulated genes.

At night, ALAN triggered activation of immediate-early genes, indicative of heightened neuronal arousal, acute neural stress, and suppression of restorative nocturnal processes. The following day, transcriptomic divergence between ALAN-exposed and control fish deepened, with widespread downregulation of genes governing vascular homeostasis, coagulation, and immune function. Together, these findings demonstrate that ALAN reshapes brain transcriptomic programs across the entire diel cycle, identifying molecular signatures of physiological disruption in light-polluted marine environments.