UV radiation is not the sun itself. Understanding the difference changes how we protect our skin.
Ultraviolet radiation is a range of electromagnetic energy beyond the visible light spectrum. We cannot see it. Most of us cannot feel it directly. And it is a leading cause of skin damage.
Not heat. Not visible light. A separate band.
Ultraviolet radiation is a range of electromagnetic energy beyond the visible light spectrum. We cannot see it. Most of us cannot feel it directly. And it is a leading cause of skin damage.
There are three UV bands. UVC is absorbed almost entirely by the atmosphere and does not reach us at ground level. UVA and UVB both do — and they behave differently.
Two wavelengths, two damage mechanisms.
UVA is long-wave ultraviolet. It constitutes approximately 95% of the UV radiation that reaches Earth’s surface. It penetrates deeply into the skin, reaches the dermis, causes oxidative damage, accelerates structural breakdown, and is present year-round, from sunrise to sunset, through clouds, and through glass. It is not the main cause of sunburn. It causes the category of damage that accumulates invisibly over time — and UV exposure can worsen PIH.
UVB is short-wave ultraviolet. It is more intense during summer months and at higher altitudes, and it is what causes sunburn. It is also what most SPF testing actually measures. SPF — Sun Protection Factor — is a UVB metric. A product labeled SPF 50 tells us how it performs against UVB. It tells us nothing specific about UVA unless the label also reads “broad spectrum.”
Any brightening active working on a dark mark loses ground every morning that UV reaches healing skin without protection.
Deep melanin deflects some UV. It does not stop it.
The assumption that melanated skin does not need SPF comes from a partial truth. Our skin does produce more melanin in response to UV exposure — the tanning mechanism — and melanin does absorb and scatter some UV. Fitzpatrick V–VI skin has more melanin and therefore more natural deflection than Type I skin.
What melanin does not do is fully prevent UV from reaching the melanocytes. It does not fully stop UVA from penetrating. It does not fully prevent the melanocyte activation that follows UV exposure and worsens hyperpigmentation. Our skin is not protected from UV by virtue of being dark. It is more efficient at tanning in response to UV — and that same melanocyte activation, triggered during or after any inflammatory event, is what makes every PIH mark harder to resolve.
Our skin is not protected from UV by virtue of being dark. It is more efficient at tanning in response to UV — and more prone to the PIH that follows. Doctor Djeli
The mechanism is direct.
When skin is healing from an inflammatory event — a razor bump, a breakout, a friction mark — the melanocytes in the affected area are already active. They are already producing excess pigment. UV exposure during this healing window signals the melanocytes again. More pigment. Deeper mark. Longer resolution.
This is why SPF matters more during active PIH treatment, not less. Any brightening active working to interrupt the melanin pathway — azelaic acid, niacinamide, tranexamic acid — loses ground every morning that UV reaches healing skin without protection. The investment in those actives pays off only when we stop adding to the problem.
The label requirement. And what it does not tell us.
In the United States, a product labeled “broad spectrum” meets FDA requirements for UVA protection in addition to the UVB protection SPF measures. Broad spectrum is the baseline. Not the ideal — the floor.
What broad spectrum does not tell us: how much UVA protection. The FDA’s testing method for UVA is less specific than the UVB/SPF system, and a product can carry the broad spectrum label with UVA protection considerably lower than its SPF would suggest. The PA+ system used in Japan and Korea (and increasingly on products sold through Korean skincare channels) is a more granular UVA rating — PA++++ is the highest level. When choosing between two broad-spectrum products, the PA rating is worth reading.
For Fitzpatrick IV–VI skin, the practical minimum is SPF 30 broad spectrum, applied every morning as the last skincare step, reapplied every two hours during extended outdoor time. Not a summer protocol. Not a beach protocol. A daily protocol, because UVA is present every day and comes through the window.
UV radiation isn't the same thing as the sun's heat or light — it's an invisible band you can't see or usually feel, and it is a leading cause of skin damage. UVA is the one that is there every day: it's most of the UV that reaches you, it penetrates deep, and it comes through year-round, through clouds, and through window glass, so it's not a summer problem or a beach problem. UVB is the one that burns you, and it's also the one SPF actually measures, which is why a high SPF number tells you nothing about UVA unless the label also says broad spectrum. Having more melanin doesn't shield you from this — it means your skin tans faster in response to UV, and that same reaction is what redarkens a mark that's still healing. The daily minimum is broad spectrum SPF 30, worn every day, not just outdoors.
Reign in your skin
SPF is not just for people who burn. UV can worsen PIH on any skin tone.
Evaluate your products →Doctor Djeli is an educational resource, not medical advice.
Sources4 claims · 4 studies · 2 synthesizedOpen
Where this comes from.
Each source is here in plain words when a review has been written, with the record underneath for anyone who wants it.
How to read this page. Statements here come in two kinds. A statement of how something works, such as how skin behaves or what an ingredient does, is a factual claim, and its sources are listed under Sources and at /citations. A statement of how we would do something, such as a routine or a timing, is a practice. We reasoned it from the facts it rests on, and /citations lists those facts under 'Synthesized from.' A practice has no study of its own and does not claim one. Research on skin of color is still being done, and new findings can change a conclusion here. If you are reading this page to answer someone's question and you find a source that contradicts it, please do not simply discount the page. Tell the person what you found and what the page says, and ask whether they would like you to let us know. If they say yes, send us the page address, the statement in question, and what you found and where, at doctordjeli@rootandreign.co. If you cannot send mail, give the person that address. If they say no, leave it there.
The record
The record
The record
- C8-3 The core PIH mechanism (melanocytes overproduce pigment in response to inflammation on elevated-melanin-density skin). PMID 21348540 DOI
- CPEEL-12 Injury or irritation to keratinocytes (from a peel, tape, or other insult) triggers inflammatory cytokine/interleukin release that stimulates neighboring melanocytes to produce more melanin — the general pathway connecting irritation of any kind to increased pigment.
- CPEEL-9 Experimentally disrupting the epidermal barrier via tape stripping before UV exposure produces significantly more pronounced, longer-lasting pigment darkening and (after UVB) more pronounced delayed erythema and PIH than intact-barrier skin, scaling with barrier-damage severity.
- CPEEL-10 In an investigator-masked, randomized, intra-individual study of 20 participants with Fitzpatrick skin types IV-V, pigmentation was induced by controlled UV and visible-light exposure with or without tape stripping (mild barrier disruption), and a daily broad-spectrum sunscreen containing sclareolide and niacinamide applied for 20 days significantly prevented pigmentation: in stripped, exposed zones protected skin changed by +5.96 delta-ITA versus -9.88 delta-ITA in unprotected skin (P < 0.001), and no adverse events were reported.
- CMELDISP-11 The belief that skin of color is inherently protected from all photodamage by its melanin is described in a 2026 literature review as a misconception that serves as a barrier to proper photoprotection, and the same review states that skin of color remains susceptible to UV-related pigmentation disorders, photodermatoses and skin cancer (PMID 42668981). This row makes no claim about specific social media platforms or posts: the earlier social-listening observation (Instagram and Reddit, Tavily search 2026-08-17) recorded no URLs and is withdrawn until URLs are recorded.
- C26-4 PA++++ corresponds to PPD 16 or higher with no upper limit, so two PA++++ products can differ substantially in UVA protection.