The Skin and Circadian Rhythm

And the importance of good sleep.

We all know of the importance of sleep but if you are like me, you probably abused your night rest by staying up and working and studying late. It’s okay, we say! We are young and strong. As time goes by we feel the lack of sleep more and wish we could have slept more!

Did you know that circadian rhythm affects most of our organs and the skin is no exception. Our master clock is in the Supra Chiasmatic Nucleus (SCN) of the anterior hypothalamus.

The SCN is greatly influenced by light. Not surprising , night shift workers have a harder time falling asleep and now we know that night shift workers and flight attendants for instance are at increased risk of certain diseases, including some forms of cancer (1), The SCN controls by feedback looks and complex mechanisms the homeostasis of circadian clock genes and the proteins they produce in target organs. The pineal gland also works with the SCN by producing melatonin a hormone that controls sleep- awake cycle . New research shows how much more importante melatonin is, even having effect on the skin! (2) Melatonin has been associated with hair growth, wound healing, anti tumor effects and even modulation of UV light damage. Melatonin has antioxidant effects. No wonder our sleep is so important!

Skin’s Circadian Cycle (3)

During the day :

Highest skin protection

Highest skin thickness

Highest sebum production

Highest pH of stratum corneum

Lowest cell proliferation

At night:

Highest DNA repair

Highest cell proliferation

Highest skin temperature

Highest barrier permeability

Highest skin penetration

Highest itching

Highest moisture loss (this is TEWL, not sweating)

Highest skin blood flow

Lowest barrier recovery rate. The skin barrier is at its most delicate time.

This explains why people with itchy skin conditions like eczema suffer more at night. Knowing the circadian physiology of the skin, may also help with better therapeutic approaches to skin conditions.

These are relatively new knowledge that scientists and doctors have discovered. There is still so much more to learn. It is interesting how melatonin or lack of melatonin affects our immune system , dysregulating it and perhaps leading to disease states. It was found for instance that people with psoriasis tend to have lower melatonin levels. Cause and effect has not been proven, but it is an interesting association. (4)

With this knowledge we have even more reason to try to have a healthier sleep.

We know that sleep deprivation for prolonged periods of time or accumulated poor sleep can slow down our mental faculties as if we were intoxicated in the extreme cases. with a society demanding action and constant connection, we lost the art of slowing down and turning within.

What can we do to sleep better?

Experts say we are too wired to our electronic gadgets. One simple action is to disconnect from electronics at least 1 hour before our set bed time. Having a regular bed time routine and schedule is imperative for a restorative sleep. Having a designated place to sleep is also one of the requirements that we are fortunate enough to have. Avoid bringing work to the bedroom and avoid television and other sources of bright light in the bedroom. Some people do well with calm music or white noise, while others prefer complete silence. If you suffer from tinnitus , white noise may actually help, so you don’t hear the constant buzzing in your ears when there is completely silence. One important message here is : too much light does not allow the pineal gland to produce physiologic levels of melatonin at night and that can have significant health implications. It’s interesting that the modern Homo sapiens has to pay attention to sleep in order to have a good sleep!



(1) Schermanhammer ES, Kroenke CH, Laden F, Hankinson SE. Night work and risk of breast cancer. Epidemiology. 2006;17(1):108-111

(2) Kleszczynski K, Hardkop LH, Fischer TW. Differential effects of Melatonin as a broad range UV-damage preventive dermato-endocrine regulator. Dermatoendocrinol 2011;3(1):27-31

(3) Lyons A.B., Moy L., Moy R., Tung R. Circadian rhythm and the skin: A Review of the Literature in the Journal of Clinical and Aesthetic Dermatology. Sept 2019; 12 (9):42-45.

(4) Mozzanica N, Tadini G, Radaelli A, et all. Plasma melatonin levels in psoriasis. Acta Derm Venereol. 1988;68(4):312-316.

Published by elianamckee

I have been a physician for many years who is now developing my entrepreneurial side with an indie beauty brand, Eirwen. Eirwen is a beauty indie company that helps perimenopausal women with their skin needs. We are launching in 2023.

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