In order to feel good, it is important to have a healthy and stable biorhythm. We can support this by getting up and going to bed at the same time every day. The inner clock is also stimulated when we have a good breakfast in the morning, because the increase in available energy via blood sugar boosts the metabolism. Conversely, it is beneficial not to eat for a few hours before going to bed, as this would put unnecessary strain on the body, which is now preparing for a period of rest and regeneration.
And this is where we begin to understand the complexity of the biorhythm. Not only our brain, our mind, is subject to the biorhythm, but also our body. It is imperative that all organs and even the skin are controlled by the daily ups and downs of metabolism. Because hormones secreted by the brain and the metabolism regulate the internal clock in every part of the body.

Are you stressed out? Do you have trouble getting out of bed in the morning? In the current situation of the pandemic and the downed air traffic, this is hardly due to jet lag after a long flight. However, our modern lifestyle causes daily jetlag, especially in stressful situations such as the COVID-19 crisis. All this stress and unfamiliar new working conditions make everything very confusing and we sometimes simply wish we could have a long sleep. 

But even without the current situation, it is hardly possible for us to maintain the natural biorhythm of daytime activity and night-time rest. It is determined by the course of the sun: when it gets light, we are awake, when it gets dark, it doesn't take long before we are tired. The reason for this is that light, especially the blue part of the spectrum, is absorbed by the eyes and sends a signal to the brain that it is time to boost the body's functions in order to perform during the day. While our ancestors still used the campfire to prolong the time it takes to go to sleep, visual media such as television or tablets/smartphones are often used in modern times. In contrast to the campfire, however, these emit blue light, which has been proven to disturb the biorhythm. This contributes significantly to the fact that we have trouble falling asleep or waking up in the morning.
We can see what a strain this can be in many elderly people, whose biorhythms are slowly but surely becoming unbalanced as they age. They suffer from waking up at night or become tired during the day.

The optimal protective function of our skin is controlled by this 24-hour rhythm, also known as the circadian rhythm, which has been fixed in our genetic material and cell metabolism over millions of years through evolution. Every day in the evening, the stem cells divide in the stratum basale, the lowest layer of the epidermis. They produce a new generation of cells which, when pushed upwards, ultimately protect our skin from environmental influences and dehydration as part of the skin barrier. But why does this happen in the evening? One reason may be that the skin is weakened during the time of regeneration. In the course of the night, we have the least moisture and the weakest skin barrier. In the early morning the skin is most sensitive and prone to itching. However, when we sleep in our natural biorhythm, we do not notice any of this and we cannot further damage the already weakened skin barrier by scratching or other mechanical stress.
At the beginning of the day, the inner clock of the cells is activated and the metabolism is boosted. The skin barrier is strengthened again and can withstand the environmental influences. Interestingly, the skin barrier is strongest in the afternoon, which may be due to the fact that even then the stress on the skin is at its greatest. Due to the constant bombardment with harmful UV or HEV radiation from the sun, the cells are attacked, accumulate DNA-, protein- and lipid-damage and have to be repaired at great expense. We can see this in the increased redness of the skin in the afternoon and evening.

Now one can imagine that due to jet lag, e.g. after a long haul flight, the skin's internal clock runs asynchronously with the new daily rhythm at the destination. As a result, the regeneration phase, in which the skin is most sensitive, is shifted to the daytime and we feel this directly, e.g. through increased itching and dry skin or a longer lasting reddening of the skin. This even leads to the skin feeling slack and wrinkles becoming more visible. It takes about 7-10 days until the body finds its new rhythm.
It is therefore easy to imagine that a constant "living against the inner clock", e.g. through shift work, stress at work, staying awake for long periods using electronic media, will have an effect on the skin. Generally, dry, irritated and reddened skin is the result.

Of course, we cannot use cosmetics to change the lifestyle of consumers or even intervene in their hormone balance to influence their internal clock. So, we have to consider what is the biggest influencing factor for the disruption of the epidermal clock. In doing so, we quickly come across the need to prevent as much damage as possible to the DNA, because only a completely intact DNA allows the stem cells to divide and regenerate the skin. The greatest danger is therefore UV and HEV light, which either cause direct DNA damage or induce reactive oxygen species (ROS) that indirectly damage the DNA. But also cell metabolism alone generates ROS. The more stressed the cells are, the more ROS are produced. In itself, the cell has developed effective mechanisms to counteract this. But at some point, the stress limit is exceeded. In our experiments, we could clearly see that UV radiation massively disturbs the mechanisms controlling the epidermal clock and throws it out of balance. We could also show that blue light leads to a massive increase in intracellular ROS. 

The task of cosmetics cannot be to fight against the natural biorhythm, but to support and strengthen it. Stem cell protection and the quickest possible restoration of DNA function are the best protective measures to keep the skin's internal clock in balance. The best way to do this is to use very strong water-soluble antioxidants that can protect the cell from the inside against ROS and UV radiation. CELLIGENT® (INCI: Helianthus Annuus (Sunflower) Seed Oil, Ethyl Ferulate, Rosmarinus Officinalis (Rosemary) Leaf Extract, Tocopherol) uses two of these: Ethyl Ferulate, obtained from rice, is a natural UV-absorbing molecule with excellent antioxidant properties. It is synergistically supported by carnosic acid from rosemary. Together, these active ingredients prevent the formation of thymidine dimers through direct UV exposure, stimulate DNA repair and eliminate harmful ROS. An effective stem cell protection as well as the restoration of the cellular biorhythm have been shown with these active ingredients. In in-vivo experiments, it was shown that this protection acts directly against the signs of epidermal jetlag: Afternoon redness is reduced, the skin is better hydrated and the skin barrier is strengthened. In addition, the skin's ability to regenerate after sunbathing increases significantly. With the active, we therefore have an intelligent, natural cell protection that has a positive effect on the skin day and night and supports the skin's natural biorhythm.