Overnight, keratinocytes (kind of skin epidermis cell) proliferate rapidly, preparing and protecting our outer barrier for the sunlight and scratches of the coming day. During the day, these cells then selectively switch on genes involved with protection against the sun’s ultraviolet (UV) rays. A 2017 study [1,2] found that midnight feasts could actually cause sunburn. If we eat late at night, our skin’s clock assumes that it must be dinner time and consequently pushes back the activation of the morning-UV-protection genes, leaving us more exposed the next day. So while studies are increasingly showing that a lack of sleep is detrimental to our overall physical and mental health, it now seems that our skin also benefits from additional sleep. The epidermis may be built to face the outside world, but it’s increasingly clear that it also looks inwards, even at when we choose to eat.
Melasma is a common skin problem caused by brown to gray-brown patches on the face. Most people get it on their cheeks, chin, nose bridge, forehead, and above the upper lip. 90% of patients are women. Although the exact pathogenesis of melasma is unknown, it is hypothesized that following exposure to UV irradiation or another inducer, hyperfunctional melanocytes within involved skin produce increased amounts of melanin [3,4].
Utraviolet (UV), A form of electromagnetic radiation that has a shorter wavelength (and higher energy) than visible light but a longer wavelength than X-rays. Roughly 10 per cent of the radiation produced by the sun is ultraviolet.
- Wang, H., van Spyk, E., Liu, 4., Geyfman, M., Salmans, M. L., Kumar, V., Ihler, A., Li, N., Takahashi, J. S. and Andersen, B., ‘Time-restricted feeding shifts the skin circadian clock and alters UVB-induced DNA damage’, Cell Reports, 20(5), 2017, pp.1061–72
- Regmi P, Heilbronn LK. Time-Restricted Eating: Benefits, Mechanisms, and Challenges in Translation. Iscience. 2020 Jun;23(6):101161.
- : Melasma: a clinical, light microscopic, ultrastructural, and immunofluorescence study. J Am Acad Dermatol. 4:698–710 1981
- : Light microscopic, immunohistochemical and ultrastructural alterations in patients with melasma. Am J Dermatopathol. 27:96–1012005