Night repair mechanisms and metabolic strategies to mimic UV benefits during the day
By Anaïs BONNEFOY
Global well-being is closely linked to the performance of our biological functions, orchestrated by the circadian clock. This internal clock, synchronised with cycles of light, darkness, and even temperature, regulates many physiological processes that directly impact skin health. Although its main control centre lies in the brain, secondary clocks are present in almost every cell of the body. These are synchronised with natural light cycles through photic signals captured by the retina. The signals are then transmitted to the cells via electrical impulses, regulated by central genes such as CLOCK, BMAL1 and PER [1] [2], and relayed to secondary clocks by neural and hormonal mediators [3]. Many aspects of the skin thus follow a cyclic rhythm, including hydration, transepidermal water loss, capillary blood flow, sebum production, temperature, surface pH, and the proliferation rate of keratinocytes [4]. With the constant cellular renewal of the epidermis, the accurate synchronisation of these events is essential [5], though often disrupted by modern lifestyles.
