The circadian rhythm also influences the functioning of skin cells, especially with regard to their ability to renew and repair themselves. However, the urban day-to-day life and environmental aggressions can compromise these processes.
Our body has its own “biological clock”, which is capable of identifying the time of day and adapting its physiological functions . This “biological clock” is called circadian rhythm, and it allows the whole organism to synchronize through the presence or absence of natural light. In this regard, blue light, which is part of sun radiation, is the most relevant segment of visible light, and it is perceived by the eye retina. The nervous system then generates a hormonal response that is transmitted to the rest of the body.
How does the skin regulate its circadian rhythm?
Skin cells also undergo metabolic changes over the 24 hours a day, in order to optimize their functions . This is important because the skin, as a barrier between the human body and the environment, is exposed to different degrees of aggression during the day and night.
How do skin cells behave overnight?
The epidermis, the outermost layer of the skin, renews itself continuously by shedding the older cells and unveiling new cells. This process tends to be accelerated as soon as the sun goes down . On the other hand, the production of substances responsible for the skin's protective barrier function begins early in the morning. Therefore, the skin is less protected and hydrated during the night.
And what happens during the day?
During the day, the metabolism of epidermal cells is especially geared towards detecting and repairing damage that may occur to their DNA . This damage can occur naturally, during the renewal process of these cells, but is mainly due to exposure to ultraviolet radiation emitted by the sun. Incidentally, skin cells are able to detect exposure to ultraviolet radiation independently of our eyes, which provides them with an additional line of defense.
How to balance the circadian rhythm of the skin (and the body)?
First of all, it is essential to maintain sleep hygiene. This means sleeping an adequate number of hours, and keeping waking and bedtimes as constant as possible. Taking into account the role of blue light in regulating the body's circadian rhythm, it is also important to minimize the use of electronic devices with LED screens at night.
Additionally, we can reinforce skin’s protective mechanisms during the day by using cosmetics with antioxidant ingredients, such as niacinamide, vitamin C, vitamin E, and ultraviolet radiation and blue light protectors such as ectoine, or Inulla helenium extract. During the night, the use of cosmetics containing regenerating ingredients such as panthenol, and emollients such as sunflower and camellia oils, minimizes skin dehydration, while favoring the natural process of epidermal renewal.