Dr. Ava Shamban discusses circadian rhythm and skincare efficacy, including the role of photoreceptors in the skin, optimal ingredient timing, and the need for more research.
Ava Shamban, MD, Board-Certified Dermatologist, Ava MD, Santa Monica, California
“It’s very interesting to me the whole topic of clock genes, how it affects or body, in general, and specifically our skin,” said Ava Shamban, MD, who presented “Clock Genes and Skincare: How Our Skin’s Circadian Rhythm Plays Into Skincare” at the SCALE 2023 meeting.
“It turns out that circadian rhythm is not just a central factor in our health, but also every single organ in our body has a circadian rhythm. So that means that everything works on a 24-hour cycle.”
Clock genes tell the cell when to turn on and off different proteins, said Dr. Shamban.
“They actually control 50% of the genome… so you really have to pay attention to their function and how important that is.”
Adding to the puzzle is the presence of photoreceptors in the skin, said Dr. Shamban.
“The question is, why are they there? It’s certainly not fed to our central nervous system and interpreted as vision, but why does our skin need light receptors?”
Consider the different types of opsins in the skin, said Dr. Shamban.
“Some of them are on melanocytes and so when they’re activated it tells the melanocytes to start producing melanin, and others—no one really knows what they’re doing. But to me, I believe that they’re tightly tied to these clock genes and to the circadian rhythm of the skin itself.”
The next question, said Dr. Shamban, is what’s the role of circadian rhythm in skincare?
“Well, of course, we want to put different types of skincare on at different times of the day so that the absorption and the effect is optimized. We know looking in general at the body that circadian rhythm affects the processing of nutrients that you ingest, and, by the same token, we know that the skin is going to be able to utilize different cytokines or antioxidants at different times of the day.”
Logically, it makes sense to use certain ingredients in the morning versus the evening, said Dr. Shamban.
“We do know based on intuition, of course, that the main function through the skin during the day is to protect itself against oxidative damage. So it makes sense to apply your antioxidants in the morning. And we also know that in the evening, the skin tends to repair itself from oxidative damage as well as to process and produce new proteins. So maybe applying cytokines in the evening is important.”
But are there ingredients that should be applied in the afternoon? Should you make timing adjustments when you travel to different time zones?
“There is a little bit of research that is going on now to see what is the optimal time to apply these various actives that we have.”
According to Dr. Shamban, research is needed to better understand the presence of photoreceptors in the skin.
“The skin is parsimonious. It’s not going to spend any energy making something that we don’t really need and is not really key.”
T cells may play a role as a central regulator, taking messages generated by light exposure from outside of the skin to the internal organs, said Dr. Shamban.
“I think the mysteries of the body and how it functions so elegantly is just amazing, and the skin, of course, being my favorite organ.”
There have been several important developments in skincare, from the discovery of the microbiome to the idea of vaccines for antiaging, said Dr. Shamban.
“And then I think the circadian rhythm of the skin is going to be just as important if not more important than all of the above. And so the more we understand, the more that we can help our skin do its best to perform all the functions it’s supposed to be, from protecting us to making us look gorgeous.”