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watch on armThe skin has its own time clock or circadian rhythm that regulates the hydration of the skin.  There is a protein in the skin called aquaglyceroporin (AQP3).  AQP3 along with the body’s natural circadian rhythm helps to transport water and glycerol through the skin which is a key element in the skin’s hydration.  The skin is the largest organ in the body and water and glycerol helps to act as a protective barrier in protecting the body against infection and dehydration.

An understanding of AQP3’s rhythm helps to explain why medications and even skin care products are best absorbed by the body and the skin, especially in the evening.  Research has shown that the stratum corneum (the outer most layer of the skin) has the greatest amount of moisture in the evening.  This is why cleansing the skin at night helps to improve product penetration and restore hydration.


Lukits, A. (2014). Wall Street Journal, “Skin hydrates according to the clock”, May 27, 2014, page D2.