Inside the Melanocyte · Chapter 2 of 4
The short answer
Dark spots form when melanocytes, the skin's pigment cells, are switched on too often or for too long. The usual triggers are UV exposure, visible light, heat, hormonal shifts and skin inflammation. Research also shows that melanocytes take cues from their neighbors: skin cells, blood vessels and aging cells in the deeper layer. That network is why stubborn pigment can come back.
- 01Your melanocyte does not act alone. It listens to the cells around it.
- 02Visible light, not just UV, can trigger pigment in medium to deep skin tones.
- 03Heat and hormones can keep melanocytes active even out of the sun.
- 04These triggers are still there after a spot fades, so maintenance matters as much as correction.
Last week, we met the melanocyte: the small cell located in the bottom layer of the epidermis that produces melanin, the skin's pigment. This week, we zoom out. Because if you have ever faded a dark spot only to watch it return, the answer is rarely the melanocyte alone. It is the neighborhood it lives in.
Why is stubborn pigment more than a surface problem?
For years, pigment care focused on one target: the enzyme inside the melanocyte that starts melanin production. It helps, but it is the last step of a longer story. Researchers now describe melanin production as the end of a complex underlying process, which helps explain why spots so often return.[2]
In 2025, an international panel of 10 dermatologists and pigmentary disorder experts published a Global Consensus on the Management of Melanin Hyperpigmentation Disorders. Its message was clear: look beyond the melanocyte, to the surrounding skin environment, including deeper skin cells called fibroblasts, immune cells called mast cells, and blood vessels.[1]
Who are your melanocyte's neighbors?
Some researchers go as far as describing melasma as a photoaging condition: a sign of sun-stressed, aging skin as much as a pigment problem.[6] That changes how you care for it.
What are the main triggers?
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UV light
The classic trigger. UV light prompts skin cells to send the "make more pigment" signal to melanocytes.[2] It reaches your skin on cloudy days and through windows, all year round.
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Visible light, especially blue-violet
This is the one most people miss. Melanocytes carry a receptor called opsin-3. Visible light triggers melanin production by activating this receptor.[4] In medium to deep skin tones (phototypes III to VI), short wavelengths of visible light (blue-violet light, around 400 to 450 nanometers) can penetrate the skin and trigger pigmentation.[2][5] In one comparison, that pigmentation was deeper and longer-lasting over two weeks than pigment caused by UVA1 radiation.[3] Standard UV filters do not fully cover visible light, which is why dermatologists often recommend tinted sunscreens with iron oxides.
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Heat
A hot summer day, a sauna, a steamy kitchen. Heat activates mast cells in the skin, which adds to the activity around the melanocyte.[2] That is one reason pigment can flare even when you have been careful with the sun.
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Hormones
Melasma is much more common in women, and pregnancy and hormonal contraception are well-known triggers.[7] If you suspect a hormonal link, talk to your doctor before changing any medication.
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Skin irritation and inflammation
Harsh scrubs, picking, breakouts or an overly aggressive routine can all leave dark marks behind, especially on deeper skin tones. Gentle wins.
Nanometers: the blue-violet wavelengths of visible light that can trigger pigmentation in medium to deep skin tones, through the opsin-3 receptor. Standard UV filters do not fully cover them.
Why do dark spots come back after they fade?
Because the triggers outlast the spot. The light, the heat, the hormonal shifts and the signals from aging skin cells are still there once a patch has faded.[2] Stop all care, and the melanocyte's neighborhood can switch it back on.
You may have heard this called "pigment memory". It is not a formal scientific term, but it is a useful image. For a deeper dive, read Why Does Melasma Keep Coming Back?
Autumn still counts
Daylight, visible light and indoor heat do not take a break in fall and winter, so daily sun protection stays on your list year-round.
- Chapter 1Meet the melanocyteRead it
- Chapter 2What wakes it upYou are here
- Chapter 3How cysteamine worksComing next
- Chapter 4The pigment care protocolComing soon
How Cyspera fits
Correcting pigment works best when you also take care of the skin around it. That is why every Cyspera routine starts with daily sun protection and pairs pigment correction with skin comfort.
CYSPERA AGELESS
With Isobionic-Amide, formulated to support your skin's resilience and radiance. The daily second step after CYSPERA INTENSIVE or SENSITIVE.
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CYSPERA TOTAL SKIN
Our daily supplement, formulated with antioxidant botanicals to help support your skin's natural defenses against oxidative stress.*
DiscoverYour next step
- Switch to a tinted, broad-spectrum sunscreen with iron oxides, and reapply when you are outdoors.
- Keep heat in check during a correction phase: shade, a hat, and a break from saunas or hot yoga.
- Be gentle. No scrubs, no picking, no stacking strong actives.
- Note any hormonal timing and discuss it with your doctor.
- Keep going after the spot fades. Maintenance is part of the plan.
Frequently asked questions
Does visible light cause hyperpigmentation?
It can, in medium to deep skin tones. Melanocytes carry a receptor called opsin-3, and short wavelengths of blue-violet light, around 400 to 450 nanometers, have been shown to trigger pigmentation in phototypes III to VI. That pigmentation lasted longer than pigment caused by UVA1 radiation in one comparison.
Do I need a tinted sunscreen for melasma?
Many dermatologists recommend one. Tinted sunscreens contain iron oxides, which help block visible light that standard UV filters do not fully cover. That matters most for medium to deep skin tones, where visible light can trigger pigment.
Does heat make melasma worse?
Heat can contribute. It activates mast cells in the skin, which adds to the activity around melanocytes. Many people notice flares after saunas, hot yoga or long days in hot weather, even with good sun protection.
Is melasma linked to skin aging?
Researchers increasingly think so. Melasma skin shows more senescent fibroblasts, which release pigment-promoting signals, and a thinner, disrupted basement membrane. Some experts describe melasma as a photoaging condition.
Why do my dark spots keep coming back?
Because the triggers around the melanocyte, such as light, heat, hormones and signals from aging skin cells, are still present after a spot fades. That is why daily sun protection and a maintenance routine matter as much as the correction phase.
References
- Passeron T, et al. Global consensus on the management of melanin hyperpigmentation disorders. Journal of the European Academy of Dermatology and Venereology. 2025. doi:10.1111/jdv.70185.
- Espósito ACC, et al. Update on melasma, Part I: pathogenesis. Dermatology and Therapy (Heidelberg). 2022;12(9):1967-1988.
- Liu et al. New mechanistic insights of melasma. Clinical, Cosmetic and Investigational Dermatology. 2023.
- Regazzetti C, et al. Melanocytes sense blue light and regulate pigmentation through opsin-3. Journal of Investigative Dermatology. 2018. PMID 28842328.
- Moreiras et al. Visible light and human skin pigmentation: the importance of skin phototype. Experimental Dermatology. 2021.
- Passeron T, Picardo M. Melasma, a photoaging disorder. Pigment Cell & Melanoma Research. 2018.
- American Academy of Dermatology. Melasma: causes.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
The Cyspera Science Team and the reviewer work for Scientis SA, the company behind Cyspera. This article is educational and is not medical advice. Last updated October 26, 2026.
