Une exposition solaire brève et sans coup de soleil aide la plupart des gens, et la juste quantité dépend de votre peau, de votre latitude et de la saison. La lumière du soleil fabrique de la vitamine D, libère de l'oxyde nitrique qui fait légèrement baisser la tension artérielle, règle l'horloge biologique et améliore l'humeur. Dans une vaste cohorte de femmes, celles qui évitaient le soleil sont mortes plus tôt — de 0.6 à 2.1 années estimées, surtout de maladies cardiaques.
Ce lien est enchevêtré avec le tabagisme et la richesse, il ne peut donc pas prouver de cause. Face à ces bénéfices, les coups de soleil intermittents et les cabines de bronzage augmentent nettement le mélanome. La voie praticable est une exposition régulière et courte qui n'atteint jamais le coup de soleil, avec une précaution supplémentaire pour les peaux claires et le soleil estival de midi, et les cabines de bronzage sont un cancérogène avéré.
Findings & Outcomes
What It Is
Sunlight reaching your skin is a mix of two ultraviolet bands. Ultraviolet B is the shorter, higher-energy band. It does not travel deep, it makes vitamin D in the top layer of skin, and it causes most sunburn. Ultraviolet A is the longer band. It reaches deeper, drives most of the tanning and the long-term aging, and releases nitric oxide into the blood.
How much of this happens depends on you and on where you are:
- Skin type sets how fast you make vitamin D and how fast you burn. Fair skin that reddens easily makes vitamin D quickly; darker skin is more protected and needs longer sun for the same vitamin D.
- Latitude and season set how much ultraviolet B reaches the ground at all. A winter morning far from the equator delivers little of it; midday summer sun near the equator delivers a great deal.
- Time of day matters because ultraviolet B is strongest around midday.
What It Does
Sunlight acts through several pathways, and they point in opposite directions on very different evidence.
The benefits rest on weaker evidence. Three are mechanisms measured directly in skin and blood: vitamin D synthesis, a nitric oxide release that briefly lowers blood pressure, and the body-clock and mood signal of daylight. The fourth, longer life among people who get more sun, comes from following one large group of women for about 20 years. It shows a pattern, cannot prove cause, and travels with smoking, wealth, and baseline health. Together they support getting regular sun; none supports seeking more.
The harms rest on stronger evidence. Ultraviolet is a proven cause of melanoma and the common skin cancers.
The Research & Studies
Everything here is based on the research we have collected and checked, sorted into groups and ordered with the strongest evidence first. Click any claim to open the studies behind it.
Cancer Risk And Outcome
Les coups de soleil et l'exposition solaire intermittente augmentaient le mélanome dans 57 études, l'exposition régulière en extérieur non
Dans des dizaines d'études, des antécédents de coups de soleil et une exposition solaire intense occasionnelle augmentaient le risque de mélanome, tandis qu'une exposition solaire quotidienne régulière ne le faisait pas. C'est le fait de brûler qui compte.
En regroupant 57 études observationnelles, l'exposition solaire intermittente et des antécédents de coups de soleil étaient associés à un risque plus élevé de mélanome, tandis qu'une exposition solaire professionnelle élevée et régulière était associée inversement. Le schéma qui augmente le mélanome est l'exposition intermittente avec brûlure, non le temps passé régulièrement à l'extérieur. Measured in: 57 observational studies (case-control and cohort) of cutaneous melanoma and sun-exposure patterns, published before September 2002. Les études composantes reposent sur le rappel de l'exposition solaire et des coups de soleil, ce qui est imparfait, et les estimations varient selon la latitude et le type de peau. Cela établit une association avec un schéma d'exposition, non un seuil de dose.
The study · 1
Gandini et al., meta-analysis of risk factors for cutaneous melanoma: II. Sun exposure · Eur J Cancer 2005;41(1):45-60
Les bancs solaires augmentaient le mélanome d'environ 20 %, et de 87 % en cas de début avant l'âge de 35 ans
Les personnes ayant déjà utilisé un banc solaire avaient une probabilité plus élevée de mélanome, et commencer avant l'âge de 35 ans la faisait presque doubler. Plus de séances signifiait plus de risque.
Dans 27 études, avoir déjà utilisé un banc solaire était associé à un risque de mélanome supérieur d'environ 20 %, augmentant avec le nombre de séances, et une première utilisation avant l'âge de 35 ans était associée à un risque supérieur d'environ 87 %. Measured in: 27 observational studies of sunbed use and skin cancer, pooled in a systematic review and meta-analysis. Les études sous-jacentes sont observationnelles, de sorte qu'une confusion résiduelle par le type de peau et le comportement de recherche du soleil est possible. La relation dose-réponse et le signal lié au jeune âge sont cohérents entre les études et vont dans le même sens.
The study · 1
Boniol et al., cutaneous melanoma attributable to sunbed use: systematic review and meta-analysis · BMJ 2012;345:e4757
L'usage régulier d'écran solaire a réduit de moitié le mélanome sur une décennie dans l'unique essai randomisé
Dans l'unique essai randomisé sur la question, les adultes qui utilisaient quotidiennement un écran solaire ont présenté environ la moitié du taux de mélanome au cours de la décennie suivante par rapport à ceux qui l'utilisaient à leur guise, et les mélanomes invasifs ont diminué de manière plus nette encore. Le même essai avait montré que l'écran solaire prévient le cancer de la peau squameux courant.
Dans le seul essai randomisé portant sur l'écran solaire et le mélanome, les adultes assignés à un usage quotidien d'écran solaire pendant environ 4.5 ans ont présenté environ la moitié du taux de mélanome de ceux l'utilisant à leur discrétion au cours de la décennie suivante (11 contre 22 cas ; hazard ratio 0.50, IC à 95 % 0.24 à 1.02, P = 0.051), et les mélanomes invasifs ont diminué de manière plus nette (3 contre 11 cas ; hazard ratio 0.27, IC à 95 % 0.08 à 0.97). Le même essai avait précédemment montré qu'un usage régulier d'écran solaire prévient le carcinome épidermoïde. Measured in: 1,621 adults aged 25 to 75 in Nambour, Queensland, Australia, randomized to daily versus discretionary sunscreen from 1992 to 1996 and then followed to 2006 (the Nambour Skin Cancer Prevention Trial). La réduction globale du mélanome n'a pas tout à fait atteint la signification statistique (P = 0.051) ; le signal le plus clair concernait le mélanome invasif, sur un nombre de cas modeste. Il s'agit d'un essai unique mené dans un contexte de fort ultraviolet et de peau claire, de sorte que l'ampleur du bénéfice sur le mélanome repose sur peu d'événements.
Who this may not transfer to:Conducted with fair-skinned adults in a high-ultraviolet Australian setting where melanoma stakes are unusually high. The protective direction should carry to other fair-skinned populations, though the absolute benefit depends on local ultraviolet and skin type.
The study · 1
Green et al., reduced melanoma after regular sunscreen use: randomized trial follow-up (Nambour Skin Cancer Prevention Trial) · J Clin Oncol 2011;29(3):257-263
How it works
L'ultraviolet B produit de la vitamine D3 dans la peau, la principale source naturelle pour la plupart des gens
Votre peau fabrique de la vitamine D lorsque la lumière ultraviolette B l'atteint, et c'est de là que la plupart des gens tirent l'essentiel de la leur. Une peau plus foncée, l'hiver, une latitude élevée, l'écran solaire et l'âge réduisent tous la quantité produite.
La lumière ultraviolette B convertit un précurseur du cholestérol dans la peau en vitamine D3, la principale source naturelle pour la plupart des gens. La quantité produite diminue avec une peau plus foncée, une latitude plus élevée, l'hiver, l'écran solaire et l'âge. Que la peau fabrique de la vitamine D grâce au soleil est établi, mais la page sur la vitamine D montre qu'en ajouter davantage chez une personne déjà suffisamment pourvue n'a pas apporté la prévention élargie des maladies autrefois espérée ; l'intérêt réside dans la correction d'un déficit existant.
The study · 1
Holick, vitamin D deficiency (review of cutaneous synthesis and determinants) · N Engl J Med 2007;357(3):266-281
Heart And Vascular
L'ultraviolet A a libéré l'oxyde nitrique cutané et brièvement abaissé la tension artérielle chez 24 volontaires
Lorsque des chercheurs ont exposé la peau de personnes à la lumière ultraviolette, cela a libéré une substance chimique qui a dilaté les vaisseaux sanguins et brièvement abaissé la tension artérielle, indépendamment de la vitamine D. C'est un indice précoce, non un traitement.
Dans une petite expérience humaine, l'exposition de la peau aux ultraviolets A a libéré dans la circulation de l'oxyde nitrique stocké dans la peau et a brièvement abaissé la tension artérielle, indépendamment de la vitamine D. Cela offre un mécanisme expliquant pourquoi la tension artérielle varie selon la saison et la latitude. Measured in: 24 healthy volunteers exposed acutely to two standard erythemal doses of ultraviolet A. Il s'agissait de 24 volontaires mesurés de façon aiguë, non d'un essai portant sur des résultats de santé. Cela montre que la voie existe ; cela n'établit pas qu'une exposition solaire quotidienne abaisse de manière significative la tension artérielle dans le temps, et le même rayonnement ultraviolet comporte un coût cutané.
The study · 1
Liu et al. (Weller, Feelisch), UVA irradiation of human skin vasodilates arterial vasculature and lowers blood pressure independently of nitric oxide synthase · J Invest Dermatol 2014;134(7):1839-1846
Longevity And Mortality
L'évitement du soleil était associé à 0.6 à 2.1 années de vie en moins, une association confondue
Dans un large groupe de femmes suédoises, celles qui évitaient le soleil avaient tendance à mourir plus tôt que celles qui en recevaient le plus, d'une durée estimée à six mois à deux ans. Les décès supplémentaires étaient surtout d'origine cardiaque, non liés au cancer de la peau.
Sur environ 20 ans, les femmes qui évitaient le soleil présentaient une mortalité toutes causes confondues plus élevée que les femmes ayant l'exposition solaire la plus importante, soit une espérance de vie réduite estimée de 0.6 à 2.1 ans. Les décès en excès relevaient de causes cardiovasculaires et d'autres causes non cancéreuses, non du cancer de la peau. Measured in: 29,518 Swedish women aged 25 to 64 at enrollment, followed roughly 20 years (the Melanoma in Southern Sweden cohort). What could explain it instead: Sun avoidance is associated with things that shorten life: it correlates with smoking, poorer baseline health and less physical and outdoor activity, and people already unwell stay indoors more, so reverse causation is plausible. The analysis adjusted for several of these but cannot remove them all.. Les habitudes solaires ont été autodéclarées à un seul temps de référence, et il s'agit d'une cohorte régionale unique. Les auteurs décrivent l'ampleur de l'effet comme comparable à celle du tabagisme, et la même prudence s'applique : l'exposition a été observée, non attribuée, de sorte que ce chiffre ne peut être interprété comme un effet de traitement.
Who this may not transfer to:Measured only in women. The vitamin D, nitric oxide and circadian pathways proposed behind the signal are not sex-specific, but no men were in this cohort, so the size of the association is not established for them.
The study · 1
Lindqvist et al., avoidance of sun exposure as a risk factor for major causes of death (Melanoma in Southern Sweden cohort) · J Intern Med 2016;280(4):375-387
How It Works
Anatomy of the Practice
1Ultraviolet B makes vitamin D
The shorter ultraviolet B band turns a cholesterol precursor at the surface of the skin into vitamin D3, the main natural source for most people. Production climbs fast, then plateaus well before the skin reddens. Past that point you add skin damage without adding vitamin D. How much you make drops with darker skin, higher latitude, winter, sunscreen, and age.
2Ultraviolet A releases nitric oxide
The longer ultraviolet A band reaches deeper and frees a store of nitric oxide from the skin into the blood. In a small experiment that release relaxed blood vessels and briefly lowered blood pressure, separate from vitamin D. It may be one reason blood pressure runs higher in winter and at higher latitudes. It is still an early finding.
3Light sets the body clock
Light striking a specialized set of retinal cells sets the master clock in the brain. Morning light pulls that clock earlier; late light pushes it later. This is the pathway behind daylight sharpening morning alertness, bringing sleep on sooner, and lifting mood. It is why sun taken toward morning does the most.
4Ultraviolet damages skin DNA
The same ultraviolet that does all this also damages the DNA in skin cells. The body repairs most of it, but not all, so damage builds over a lifetime and occasionally becomes a mutation that grows. Burning doses cause the most damage. Melanoma tracks episodes of burning and past sunburns; steady outdoor work carries less of this risk.
A real vitamin D shortfall is worth correcting; adding more to someone already sufficient did little in the large vitamin D trials. Morning light in the day and darkness at night pull the body clock the same direction.
Getting the Balance Right
Ways to Do It
Almost nothing here costs money. The core is a little regular sun without burning and learning your own skin, both free. The one paid item is sunscreen, for days spent long in the sun. Start at the top.
Short, regular time outdoors with some skin uncovered lets the body make vitamin D and set the clock. Taken in the morning, it does the most for sleep and mood. Aim for warmth on the skin and stop before any pinkness. On a strong-sun day a short spell suits lighter skin; darker skin and higher latitudes need longer.
Fair skin needs less sun and reddens fast; darker skin tolerates more and needs a longer dose. Season and latitude move the same dial: high summer near the equator is far stronger than a winter morning up north. Learn how fast your own skin begins to redden, and treat that as your ceiling.
The vitamin D forms early, while the skin-cancer risk builds with the hours. So for a long day outside, the free move is a hat, a shirt, and shade. Shade around midday, roughly late morning to mid-afternoon in summer, cuts the strongest ultraviolet and leaves the gentler morning and evening sun. Clothing is the most reliable sun protection there is.
For time outdoors beyond a short sensible dose, a broad-spectrum sunscreen of SPF 30 or higher lowers burning and cumulative damage. Reapplied every couple of hours and after swimming, it holds that protection. In the one randomized trial that tested it, regular use also lowered melanoma over the following decade. Most people apply too little; a generous layer is what reaches the labeled SPF.
A tanning bed gives ultraviolet with none of daylight's benefits, and it is a proven cause of melanoma.
In a sunless winter, or for someone who cannot get outdoors, sun alone will not cover vitamin D. Oily fish and fortified foods carry some, and a daily [vitamin D3](/go/integrative/practice/vitamin-d) supplement replaces the rest with no ultraviolet.
Protect against burning; you do not need to avoid daylight to be safe from skin cancer.
Some people should lean toward less sun and more cover:
- very fair skin, or many or unusual moles
- a personal or family history of skin cancer
- a suppressed immune system
- a sunny, high-ultraviolet latitude
Darker skin at a high latitude in winter leans the other way, toward getting sufficient sun.
Go Deeper
- Vitamin D: what the sun-made vitamin does in the body, a sensible dose, and where the large trials found its limits.
- Morning light: the circadian half of the benefit, and how to get the body-clock return without seeking a tan.
- Nitric oxide and the endothelium: the blood-vessel lining and the nitric oxide pathway the skin feeds into.
- Evening light and screens: the other end of the daily light signal, protecting the dark so the daytime sun holds.
- Circadian entrainment: how light sets the master clock, the mechanism underneath the timing advice.
Cautions For This Practice
Extra restraintEverything to be aware of is here, in one place. This practice suits most healthy people; a few situations call for real care.
Never burn, and protect children especially
A sunburn is skin damage, and a history of sunburn is one of the clearest melanoma risk factors, with childhood and adolescent burns carrying particular weight. Keep children out of burning sun with shade, clothing, and sunscreen. Protect against burning; you do not need to avoid daylight to be safe from skin cancer. Cumulative ultraviolet over a lifetime also ages the skin and adds to skin-cancer risk.
Tanning beds raise melanoma risk, most when started young
A tanning bed is pure ultraviolet with none of the daylight that comes with time outside. Ever using one raises melanoma risk, and starting before age 35 nearly doubles it. The risk climbs with each session. The tan it produces is accumulated DNA damage that protects against almost no later burning, and self-tanning lotions add the same color with no ultraviolet.
Watch changing moles and spots
Have a doctor check any mole or spot that changes over time. The ABCDE signs are the guide: an uneven, Asymmetric shape; an irregular Border; more than one Color; a Diameter wider than a pencil eraser; or Evolving size, shape, or color. Also check anything that bleeds, itches, or will not heal. Caught early, melanoma and the common skin cancers are usually very treatable, so a changing spot is worth a prompt appointment.
A past skin cancer or family melanoma means much less sun
A personal history of melanoma or another skin cancer, or a close relative with melanoma, shifts the balance hard toward protection. The safe amount of sun, and how often to have your skin checked, are best set with a dermatologist who knows your history.
Some medications and conditions make skin far more sun-sensitive
Certain drugs make the skin burn much faster. They include some antibiotics such as doxycycline, some diuretics, retinoids, and St John's wort, and conditions like lupus do the same. If a medication you take lists photosensitivity, treat your usual sun tolerance as much lower and cover up or use sunscreen sooner.
A suppressed immune system raises skin cancer risk sharply
Organ-transplant recipients and others on long-term immune-suppressing treatment have a much higher rate of skin cancer. This group needs strict, consistent sun protection and regular skin checks.
Skin type changes how much sun is safe
At high latitudes, darker skin is the most likely to fall short of vitamin D, because it makes the vitamin slowly while the available ultraviolet is already low. Very fair skin has the opposite problem: it burns before it has had much sun, so it needs the most cover. Set the dose to your own skin.
Protect the eyes
Ultraviolet harms the eyes over time, adding to cataracts and other damage, and staring at the sun can injure the retina. Sunglasses that block ultraviolet are worth wearing in bright conditions. Getting morning light means facing the open sky, with your eyes off the sun itself.
Start slow, be smart, read the research, and consult a professional if you have any concerns. This is here to inform your choice, not make it for you.
Common Questions
How much sun do I actually need for vitamin D?
Less than most people picture. For lighter skin under strong summer sun, uncovering the forearms and lower legs for a short spell a few times a week is plenty. Darker skin and northern latitudes need appreciably longer for the same amount.
Is the sun or a supplement the better way to get vitamin D?
For anyone with reliable daylight, brief non-burning sun is the natural source of vitamin D. It also delivers a body-clock and mood signal a capsule cannot. Where daylight is scarce (through a dark winter, on night shifts, or for someone housebound) a small daily D3 pill restores the vitamin and nothing else.
Does sunscreen block vitamin D?
In theory it filters the ultraviolet B that starts vitamin D. In practice people spread a fraction of the tested amount and reapply rarely, so the real-world drop is small. Studies of regular sunscreen users have generally not found them deficient. Since the vitamin is made early in a session, the short daily dose that gives the benefit is largely done before a long-exposure sunscreen matters.
Explore Related
Other pages this one connects to, by the evidence they share, the outcomes they touch, and the ground they cover.
All 6 sources on this page independently checked and cross-referenced.
Thomas Dehli, Founder & Editor, Sacred Lotus
Sacred Lotus has published Chinese medicine reference material since 2001. Integrative pages are held to the same standard as the herb and formula library: cite the source, grade the claim at its real strength, and say where the research has not looked. This page is educational and it is not medical advice. Last reviewed and updated August 9, 2026.
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