Researchers have found that our skin has a biological clock that regulates repair and regeneration of skin cells.

For the study, researchers took skin samples from healthy young people at different time intervals. Analysis of the skin cellskeratinocytes showed that regeneration and repair of cells varied depending on the biological clock.

Researchers found that a molecule called the Krüppel-like-factor (Klf9) slowed down cell division in the keratinocytes. They then reduced the levels of this molecule and as expected, cells began dividing faster.

Cortisol- a hormone released at the time of stress -regulates the activity of Klf9, researchers said.

Previous research supports the idea that skin can indeed tell time. According to a commentary in the Journal of Investigative Dermatology, skin has a circadian clock that is influenced by the central clock (present in the hypothalamus of the brain). Authors of this commentary say that this circadian clock is present in almost all types of skin cells and it may contribute in cell division.

According to another study, skin cells have a very complex circadian clock and that various types of skin cells co-ordinate and follow a rhythmic pattern within the cell.

Researchers say the study could lead to advances in skin care. People can be given medication at the most optimal time of the day to match the skin's biological clock.

"If we understand these processes better, we could target the use of medication to the time of day in which they work best and have the fewest side effects," said Professor Achim Kramer, one of the authors of the study from CharitéUniversitätsmedizin Berlin, in a news release.

The study is published in the journal Proceedings of the National Academy of Sciences.