The Circadian Skin: Chronobiology as a New Frontier in Dermatological Therapy.

The skin is a temporally dynamic organ governed by intrinsic molecular clocks operating across multiple cell types. Circadian regulation influences epidermal renewal, barrier function, pigmentation, immune activity, DNA damage responses, and wound repair. This narrative review critically summarizes current mechanistic, translational, and clinical evidence linking the cutaneous circadian clock to skin physiology and selected dermatological diseases and evaluates the emerging concept of chronodermatology. A targeted literature search of PubMed/MEDLINE and reference lists of relevant articles was used to identify foundational and recent studies addressing cutaneous clock mechanisms, melanoma, atopic dermatitis, psoriasis, wound healing, photobiology, and chronotherapeutic strategies. Evidence was strongest for intrinsic circadian oscillation in skin cells, time-dependent epidermal and DNA-repair biology, and rhythmic wound-healing processes; however, many proposed therapeutic applications remain supported primarily by preclinical, observational, or early translational data. Chronodermatology therefore represents a promising framework for investigating treatment timing and individualized temporal biology, but prospective human trials are required before routine time-specific prescribing, photoprotection, or clock-targeted therapy can be recommended.