Skin has different daytime and nighttime needs, emerging circadian research suggests

SAN DIEGO – Emerging research on so-called “clock genes” suggests that the human skin has different daytime and nighttime needs, according to Ava Shamban, MD.

“Paying attention to the circadian rhythm of the skin is every bit as important as moisturizing the skin,” Dr. Shamban, a dermatologist who practices in Santa Monica, Calif., said at the annual Masters of Aesthetics Symposium. “It is paramount to both your morning and evening skin regimen routine,” she added.

Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. “These natural processes respond primarily to light and dark and affect most living things, including animals, plants, and microbes,” she said. “The circadian system is composed of peripheral circadian oscillators in many other cells, including the skin.”

The science has been around awhile, but dermatologists didn’t understand its impact until recently, she said.

In 1729, the French astronomer Jean-Jacques d’Ortous de Mairan demonstrated that mimosa leaves, which open at dawn and close at dusk, continued this cycle even when kept in darkness. In the 1970s, Seymour Benzer and Ronald Konopka showed that mutations in an unknown gene disrupted the circadian clock of fruit flies.

And in 2017, the Nobel Prize in Physiology or Medicine was awarded to Jeffrey C. Hall, Michael Rosbash, and Michael W. Young for discovering molecular mechanisms that control circadian rhythm. Using fruit flies as a model, they isolated a gene that controls the normal daily biological rhythm.

“They showed that this gene encodes a protein that accumulates in the cell during the night and is then degraded during the day, and they identified additional protein components, exposing the mechanism governing the self-sustaining clockwork inside the cell,” said Dr. Shamban.

In humans and other mammals, the primary body clock is located in the suprachiasmatic nucleus, a cluster of approximately 10,000 neurons located on either side of the midline above the optic chiasma, about 3 cm behind the eyes. Several clock genes have been identified that regulate and control transcription and translation.

“Expression of these core clock genes inside the cell influences many signaling pathways, which allows the cells to identify the time of day and perform their appropriate function,” Dr. Shamban said. “Furthermore, phosphorylation of core clock proteins leads to degradation to keep the 24-hour cycle in sync.”

Photoreceptive molecules known as opsins also appear to play a role in regulating the skin’s clock. A systematic review of 22 articles published in 2020 found that opsins are present in keratinocytes, melanocytes, dermal fibroblasts, and hair follicle cells, and they have been shown to mediate wound healing, melanogenesis, hair growth, and skin photoaging in human and nonhuman species.

“You may wonder, why does the skin respond so nicely to light?” Dr. Shamban said. “Because it contains opsins, and light exposure through opsin-regulated pathways stimulates melanin production.”

Patients can support their skin’s clock genes by understanding that skin barrier functions such as photoprotection and sebum production are increased during the day, while skin permeability processes such as DNA repair, cell proliferation, and blood flow are enhanced at night.

“Your skin has different daytime and nighttime needs,” Dr. Shamban commented. “Simply put, daytime is defense, and nighttime is offense. I think we’ve known this intuitively, but to know that there is science supporting this idea is important.”

Dr. Shamban wrote the book “Heal Your Skin: The Breakthrough Plan for Renewal” (Wiley, 2011). She disclosed that she conducts clinical trials for many pharmaceutical and device companies.

SAN DIEGO – Emerging research on so-called “clock genes” suggests that the human skin has different daytime and nighttime needs, according to Ava Shamban, MD.

“Paying attention to the circadian rhythm of the skin is every bit as important as moisturizing the skin,” Dr. Shamban, a dermatologist who practices in Santa Monica, Calif., said at the annual Masters of Aesthetics Symposium. “It is paramount to both your morning and evening skin regimen routine,” she added.

Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. “These natural processes respond primarily to light and dark and affect most living things, including animals, plants, and microbes,” she said. “The circadian system is composed of peripheral circadian oscillators in many other cells, including the skin.”

The science has been around awhile, but dermatologists didn’t understand its impact until recently, she said.

In 1729, the French astronomer Jean-Jacques d’Ortous de Mairan demonstrated that mimosa leaves, which open at dawn and close at dusk, continued this cycle even when kept in darkness. In the 1970s, Seymour Benzer and Ronald Konopka showed that mutations in an unknown gene disrupted the circadian clock of fruit flies.

And in 2017, the Nobel Prize in Physiology or Medicine was awarded to Jeffrey C. Hall, Michael Rosbash, and Michael W. Young for discovering molecular mechanisms that control circadian rhythm. Using fruit flies as a model, they isolated a gene that controls the normal daily biological rhythm.

“They showed that this gene encodes a protein that accumulates in the cell during the night and is then degraded during the day, and they identified additional protein components, exposing the mechanism governing the self-sustaining clockwork inside the cell,” said Dr. Shamban.

In humans and other mammals, the primary body clock is located in the suprachiasmatic nucleus, a cluster of approximately 10,000 neurons located on either side of the midline above the optic chiasma, about 3 cm behind the eyes. Several clock genes have been identified that regulate and control transcription and translation.

“Expression of these core clock genes inside the cell influences many signaling pathways, which allows the cells to identify the time of day and perform their appropriate function,” Dr. Shamban said. “Furthermore, phosphorylation of core clock proteins leads to degradation to keep the 24-hour cycle in sync.”

Photoreceptive molecules known as opsins also appear to play a role in regulating the skin’s clock. A systematic review of 22 articles published in 2020 found that opsins are present in keratinocytes, melanocytes, dermal fibroblasts, and hair follicle cells, and they have been shown to mediate wound healing, melanogenesis, hair growth, and skin photoaging in human and nonhuman species.

“You may wonder, why does the skin respond so nicely to light?” Dr. Shamban said. “Because it contains opsins, and light exposure through opsin-regulated pathways stimulates melanin production.”

Patients can support their skin’s clock genes by understanding that skin barrier functions such as photoprotection and sebum production are increased during the day, while skin permeability processes such as DNA repair, cell proliferation, and blood flow are enhanced at night.

“Your skin has different daytime and nighttime needs,” Dr. Shamban commented. “Simply put, daytime is defense, and nighttime is offense. I think we’ve known this intuitively, but to know that there is science supporting this idea is important.”

Dr. Shamban wrote the book “Heal Your Skin: The Breakthrough Plan for Renewal” (Wiley, 2011). She disclosed that she conducts clinical trials for many pharmaceutical and device companies.

SAN DIEGO – Emerging research on so-called “clock genes” suggests that the human skin has different daytime and nighttime needs, according to Ava Shamban, MD.

“Paying attention to the circadian rhythm of the skin is every bit as important as moisturizing the skin,” Dr. Shamban, a dermatologist who practices in Santa Monica, Calif., said at the annual Masters of Aesthetics Symposium. “It is paramount to both your morning and evening skin regimen routine,” she added.

Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. “These natural processes respond primarily to light and dark and affect most living things, including animals, plants, and microbes,” she said. “The circadian system is composed of peripheral circadian oscillators in many other cells, including the skin.”

The science has been around awhile, but dermatologists didn’t understand its impact until recently, she said.

In 1729, the French astronomer Jean-Jacques d’Ortous de Mairan demonstrated that mimosa leaves, which open at dawn and close at dusk, continued this cycle even when kept in darkness. In the 1970s, Seymour Benzer and Ronald Konopka showed that mutations in an unknown gene disrupted the circadian clock of fruit flies.

And in 2017, the Nobel Prize in Physiology or Medicine was awarded to Jeffrey C. Hall, Michael Rosbash, and Michael W. Young for discovering molecular mechanisms that control circadian rhythm. Using fruit flies as a model, they isolated a gene that controls the normal daily biological rhythm.

“They showed that this gene encodes a protein that accumulates in the cell during the night and is then degraded during the day, and they identified additional protein components, exposing the mechanism governing the self-sustaining clockwork inside the cell,” said Dr. Shamban.

In humans and other mammals, the primary body clock is located in the suprachiasmatic nucleus, a cluster of approximately 10,000 neurons located on either side of the midline above the optic chiasma, about 3 cm behind the eyes. Several clock genes have been identified that regulate and control transcription and translation.

“Expression of these core clock genes inside the cell influences many signaling pathways, which allows the cells to identify the time of day and perform their appropriate function,” Dr. Shamban said. “Furthermore, phosphorylation of core clock proteins leads to degradation to keep the 24-hour cycle in sync.”

Photoreceptive molecules known as opsins also appear to play a role in regulating the skin’s clock. A systematic review of 22 articles published in 2020 found that opsins are present in keratinocytes, melanocytes, dermal fibroblasts, and hair follicle cells, and they have been shown to mediate wound healing, melanogenesis, hair growth, and skin photoaging in human and nonhuman species.

“You may wonder, why does the skin respond so nicely to light?” Dr. Shamban said. “Because it contains opsins, and light exposure through opsin-regulated pathways stimulates melanin production.”

Patients can support their skin’s clock genes by understanding that skin barrier functions such as photoprotection and sebum production are increased during the day, while skin permeability processes such as DNA repair, cell proliferation, and blood flow are enhanced at night.

“Your skin has different daytime and nighttime needs,” Dr. Shamban commented. “Simply put, daytime is defense, and nighttime is offense. I think we’ve known this intuitively, but to know that there is science supporting this idea is important.”

Dr. Shamban wrote the book “Heal Your Skin: The Breakthrough Plan for Renewal” (Wiley, 2011). She disclosed that she conducts clinical trials for many pharmaceutical and device companies.