Clock genes

Good news for Sleeping Beauty

Chronobiology is the science that studies biological rhythms. It is based on a fundamental discovery: that all living beings, including humans, animals, and plants, live according to precise rhythms influenced by external time factors such as the day/night cycle. All our internal systems operate on regular modes generally in rhythm with the year, month, or day.

Chronobiology and the skin
Skin is no exception to this rule of nature; it also works on periodic modes, with its own biological rhythms.

Indeed, research in chronobiology shows that several characteristic parameters of the skin vary according to the circadian rhythm; for example, the temperature of the skin, sebum, pH, and transepidermal water loss.

For skin, these rhythms are orchestrated by the clock genes. These give a tempo to the cell, orchestrating and modulating more than 20 per cent of gene expression.

Desynchronization and aging
Time is an important factor in skin cells so that they can anticipate and adapt their roles and activities throughout the day. Not only do they need to be able to adapt to their environment and in particular the alternation of day and night, but also all work together for optimum efficiency.

In 2001, researchers identified the first human clock gene. Since then, they have also revealed that each skin cell contains its own clock gene. The synchronization of these genes provides natural protection and enables reparation of our skin. Thus, in general, thanks to these genes, throughout the day our skin cells protect themselves against environmental stresses, while at night they turn on all functions related to repair, to correct the damage caused that day.

However, with time and exposure to UV—even at low doses–the expression of clock genes decreases. Cells are no longer able to tell the difference between day and night. Basically, they are out of sync. They provide less protection and are less able to repair. As a result, the skin ages more quickly.

A smart peptide to the rescue
It is thanks to an intelligent tetrapeptide—capable of stimulating the natural synchronization process of each cell—that some treatments are now able to slow down the process of premature aging of the skin. This innovative molecule puts the record straight by boosting clock gene expression in order to preserve biological circadian rhythms. It acts as a metronome to allow the cells to regain their full capacity for optimal protection and self-repair. It also helps to anticipate environmental aggressors before they damage the skin. Thus the processes of protection and repair of the cell are optimized to achieve youthful skin for longer.

Did you know…

For skin of a person who goes to sleep at 11 p.m. and wakes at 7 a.m.:

  • The secretion of sebum is minimal at 4 a.m. and greatest at 1 p.m.
  • Water loss is greatest at 8 p.m. and minimal around 9 a.m.
  • pH values are greatest around 3 p.m. and minimal in the evening
  • Dermal absorption peaks at 4 a.m. and is at its minimum in the evening
  • The capillary microcirculation is higher during the night
  • Skin reactivity is weaker during the day and elevated at night
  • The peak of cell division is observed around midnight or 1 a.m.



Isabelle Villeneuve is scientific director—head of innovation at Laboratoire Dr Renaud. She has been actively participating in the development of Laboratoire Dr Renaud since 1995.

by Isabelle Villeneuve | Spring 2013