the skin ’ s circadian rhythm
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Your skin ’ s natural nightly rhythm by Professor Gaby Badre
THE SKIN IS A BARRIER DEFENDING THE BODY against microorganisms and environmental factors , many with hour-by-hour variations including pollutants , light , solar ultraviolet radiation , humidity , temperature and exposure to bacteria . To respond to these changing environmental stressors , there is a constant oscillation of the skin properties regulated by
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… EVENINGS AND NIGHTS ARE THE TIME FOR INTENSE CLEANS- ING AND REGENER- ATION , AS WELL AS SKIN PROMOTING ITS RENEWAL .
“ the biological clock .
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Many attributes of the skin therefore have a cyclic pattern : water loss and hydration , blood flow , sebum production , surface temperature and pH , cell proliferation rate , even visibility of facial rhytides ( wrinkles ). Skin response to UV radiation has also a daily rhythm .
During the day skin plays the role of a shield against environmental aggressors . It is during this time that there is the highest skin barrier protection , highest skin thickness , highest pH , highest sebum production ( lubricating the skin and protecting against infections , but also putting it at risk of clogging and promoting growth of bacteria ) as well as the lowest cell proliferation .
Free radicals accumulate during the day and damage is at its height when the skin is exposed to environmental stressors . Conversely , evenings and nights are the time for intense cleansing and regeneration , as well as skin promoting its renewal . Hence it is during this time that you experience the
“ highest DNA repair , highest cell proliferation ( when skin stem cells create new cells replacing CHRONIC SHORT SLEEP aged ones ), highest skin temperature , highest
AND DISRUPTION OF CIRCADIAN RHYTHM skin permeability ( skin barrier being less ARE ALSO CORRELATED optimal ), highest skin penetration , highest
WITH SIGNS OF ACCEL-
ERATED SKIN AGEING . moisture ( water ) loss , highest skin blood flow , but lowest barrier function and also it is the time for highest itching ...
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