Impact of acute blue light irradiation on the molecular clock and markers associated with photoaging in skin cell models.

The increased reliance on digital devices in our daily lives has exposed humans to intense levels of high-energy blue light. However, the harmful effects of blue light irradiation on human skin are less understood than UV irradiation. Notably, we demonstrated that blue light induces skin photoaging through a novel mechanism involving disruption of the circadian rhythm. An in vitro study using human keratinocyte cells and dermal fibroblasts was conducted. The results showed that blue light irradiation triggers cellular senescence and downregulates key aging-associated markers, including extracellular matrix components, epithelial barrier protein, NAD+-dependent metabolic stress sensor (SIRT1), and aging-sensitive NAD + producer (NAMPT). Remarkably, we found that blue light irradiation disrupted the circadian rhythm at the cellular level. This is evidenced by phase-shifted PER3 mRNA levels, loss of BMAL1 protein rhythmicity, and altered temporal expression of aging-associated markers. Our results demonstrate that blue light triggers skin photoaging through circadian disruption, establishing a novel mechanistic pathway that transforms our understanding of photoaging complexity. This study initiates the framework for developing chronotherapy-based interventions to address the growing epidemic of digital device-associated skin damage and, therefore, could be used as a scientific foundation for developing novel active compounds in cosmeceutical products. KEY MESSAGES: We identified novel mechanisms in blue light-induced skin photoaging. Acute blue light exposure induced cellular senescence in skin cells. Acute blue light exposure downregulated key aging-associated markers in skin cells. Acute blue light exposure disrupted the circadian rhythm of skin cells. Targeting circadian rhythm offers a promising therapeutic route for skin photoaging.