Published: June 16, 2020
Updated: July 16, 2025
Stay Healthy in the Sun: Your Guide to Safe Sun Exposure
Summer has arrived in the northern hemisphere, bringing warmth and relief after the cold winter months. We know you’re eager to enjoy the sun and the pleasant weather, but before you do, it’s important to take a moment and understand what you’re exposing yourself to.
This article will help you understand how to enjoy safe sun exposure and provide some practical tips to protect your health.
Why Sunlight Matters for Your Health
Sunlight can be a good friend of ours, especially as it stimulates the assimilation of vitamin D by our body and contributes to the well-being of our hormonal system.
Beyond that, sunlight helps regulate our body clock. This natural 24-hour clock (called circadian rhythm) influences how well we sleep, how alert we feel, and our overall health [1]. It also prevents other conditions such as heart disease, metabolic syndrome, obesity, myopia, neurodegenerative disorders, as well as low mood. It achieves this through the activation of several chemicals in the body like serotonin, dopamine, and nitric oxide, that respond to UV exposure [2].
However, abuse of exposure to sunlight can become harmful for your overall health. According to the World Health Organization [3] “...Exposure to the sun is known to be associated with various skin cancers, accelerated skin ageing, cataracts and other eye diseases, and possibly has an adverse effect on a person’s ability to resist infectious diseases.”
How do we get vitamin D from sunlight?
According to the National Institutes of Health (NIH) [4], sunlight is essential for vitamin D synthesis. When your skin is exposed to ultraviolet (UV) radiation from the sun, it starts a natural process that produces vitamin D3. This form of vitamin D3 is then transported to the liver and kidneys where it’s turned into its active form, which the body uses for vital functions such as calcium absorption, immune system support, and cell growth.
Vitamin D from Sunlight Vs Dietary Supplements
Naturally, you may wonder if taking vitamin D via dietary supplements can offer the same health advantages as sun exposure. While supplements can help increase vitamin D levels, they fail to replicate all the benefits associated with ultraviolet (UV) radiation. Therefore, moderate sun exposure is essential for good health, supporting both vitamin D synthesis and additional vital processes beyond the reach of supplements alone [5].
UV Radiation - Types and Effects
According to an article published in the International Journal of Molecular Sciences (2013) [6], sunlight contains different types of UV rays: UVA, UVB, and UVC. Each form of radiation has different effects on the human body:
- UVC radiation (100-280 nm): This is the highest-energy ultraviolet radiation, but it doesn’t reach us because it is almost entirely blocked by the Earth’s ozone layer.
- UVB radiation (280-315 nm): This is a mid-energy UV, making up approximately 5-10% of ambient sunlight (the natural light present in the environment). Almost all of it is absorbed in the outer layers of the skin and can directly cause DNA damage and sunburn.
- UVA radiation (315-400 nm): This is the lowest-energy type of UV radiation, comprising about 90-95% of ambient sunlight. It penetrates deeply into the skin and can generate unstable molecules (called free radicals) that harm skin cells and DNA over time, contributing to dark spots, age spots, and other signs of skin aging.
How Much Sun Exposure Is Safe
To safely enjoy sunlight and support vitamin D production, it is important to find the right balance [5]. The amount of sun needed varies based on a mix of personal and environmental factors l ike skin type, latitude, and time of day. Here’s what can affect how well your skin turns sunlight into vitamin D:
- Time of day: UVB rays are most intense between 10 a.m. and 3 p.m.
- Season and latitude: In winter or at higher latitudes, UVB rays are weaker, reducing vitamin D production.
- Skin pigmentation: Individuals with fair skin or lighter skin tones (less melanin) require less sun for vitamin D synthesis, while those with darker skin, due to higher melanin content, have more natural protection but may need longer exposure to produce the same amount of vitamin D.
- Age: Older adults have a reduced capacity to produce vitamin D.
- Use of sunscreen or clothing with UV protection: Both block UVB rays and significantly reduce vitamin D synthesis.
Generally, according to Harvard Medical School, sessions of around 10 to 15 minutes of sun exposure on areas like the arms and legs, a few times per week, can generate most of the vitamin D needed to maintain healthy levels [11].
Sunlight exposure should be balanced carefully to ensure adequate vitamin D levels while minimizing the risk of skin damage. When exposing skin without sunscreen, consider your skin tone and the current UV level. Always stay alert to any signs of skin redness or discomfort and seek shade when UV light levels are high for your skin health [5].
What are the symptoms of too much sun exposure
Spending too much time in the sun, especially without protection, can lead to some harmful effects on the skin, eyes, and overall health. Common signs and conditions linked to overexposure include [6]:
- Sunburn: Characterized by red, painful swollen skin that may blister after being in the sun
- Photoaging: Premature wrinkles, skin thinning, loss of elasticity, and uneven pigmentation caused by chronic UV exposure.
- Photodermatoses (sun-triggered skin reactions):
- Polymorphic light eruption: Itchy red bumps or blisters appearing after sun exposure.
- Solar urticaria: Sudden hives or welts occurring within minutes of sun exposure.
- Photo-allergic and photo-toxic reactions: Rashes or exaggerated sunburn in individuals sensitive to sunlight or certain medications and chemicals.
- Worsening of existing skin disorders: Including flare-ups of rosacea and discoid lupus.
- Actinic keratosis: Rough, dry patches caused by long-term UV light exposure can turn into skin cancer over time if not treated.
- Weakened skin immunity: Ultraviolet rays can make the skin’s defenses weaker, which may increase infections or reduce the ability to fight early signs of skin cancer.
- Eye damage: Increased risks of cataract formation, vision problems, or sunburn in the eyes.
- Worsening of certain health conditions: Like lupus or porphyria.
- Skin cancer: Long-term sun damage can lead to different types of skin cancer, like basal cells, squamous cells, and melanoma.
- Heat-related illnesses: Being in the sun for too long can also cause heat exhaustion or even heat stroke.
Protecting yourself with appropriate sun safety measures is essential to minimize these risks.
How to Protect Your Skin from Harmful UV Rays
Wear Sunscreen
Sunscreen helps protect against UV-induced skin damage such as sunburn, premature aging, and reduces the risk of skin cancer [10]. Here are a few essential guidelines for sunscreen effectiveness:
- The American Academy of Dermatology recommends everyone to use sunscreen that offers the following:
- Broad-spectrum protection (protects against both UVA and UVB rays)
- SPF 30 or higher
- Water resistance
- Dermatologists recommend using sunscreen every day when you are outside, not just during the summer.
- Don’t skip sunscreen on cloudy, foggy, rainy, or overcast days. UVA rays can still penetrate the skin even without direct sunlight exposure or having a ray of visible light coming from the sun [7].
- Reapply sunscreen at least every two hours, and more often if you're sweating or swimming [8].
- Use enough sunscreen to fully cover your face and body. For the average person (adults and children), this means using about one ounce (the equivalent of a shot glass) to ensure even coverage from head to toe [8].
Find the sunscreen suited for your skin type and surroundings
Not all skin reacts the same way to the sun. According to Thomas B. Fitzpatrick, an American dermatologist who created the well-known phototyping scale in 1975, we can all be divided into six skin types [9]. Choosing your sunscreen according to your phototype makes a big difference in how well you're protected. This becomes especially important if you live in or plan to travel to regions such as Australia and New Zealand. There, the ozone layer (protecting the atmosphere from UVA and UVB rays) is depleted to such an extent that it leaves “holes”, causing higher UV exposures [3]. Ozone holes have now also been reported over parts of Europe and North America [3].
Additionally, consider your surroundings when choosing sunscreen. If you’re going to be near any flame source (such as a grill, candles, or someone smoking) avoid sunscreens with flammability warnings and opt for a non-flammable option instead. This is especially important for children, who are often active and may come close to heat or flames [8].
Read labels and check the expiration date of your sunscreen
If used daily and in the correct amount, a bottle of sunscreen shouldn’t last very long. However, if it’s past its expiration date, it’s best to discard it, as expired sunscreen may no longer provide effective protection [10].
If there’s no expiration date listed, follow the general guideline: do not use sunscreen that’s more than three years old. According to the FDA, sunscreens should maintain their original strength for at least three years unless otherwise stated by the manufacturer.
Wear protective clothing
Wearing protective clothing is a highly effective way to shield your skin from harmful UV rays. Opt for garments like long-sleeved shirts, long pants, and wide-brimmed hats to cover as much skin as possible. For added protection, choose clothing labeled with an Ultraviolet Protection Factor (UPF) rating. UPF indicates how much UV radiation a fabric allows to reach your skin; for example, a UPF 50 fabric blocks 98% of UV rays [7].
Remember, while UPF clothing significantly reduces UV exposure, it should be used with other sun safety measures.
Drink water and hydrate your skin and mouth
When exposed to intense sun, we tend to lose a lot of water through sweat (a natural protective measure of the body to regulate its temperature). Hydration isn’t just important for the body; it also plays a key role in maintaining oral comfort, especially for those suffering from dry mouth. Summer can make this condition even more challenging because of the high temperatures and increased fluid loss. Learn more about how to treat dry mouth.
Adults under 60 are generally advised to drink 30 ml of water per kilogram of body weight, although this amount can vary depending on several factors such as age, gender, physical activity, and outside temperature. During hot weather, health professionals recommend drinking at least 2L of water per day, and even more with physical activity.
Eat colorfully with fruits and veggies
We have already discussed how our diet influences our overall well-being, and, especially in the summer, what we eat can have a big impact on our quality of life. Vitamins are usually beneficial for us when consumed in appropriate amounts, and some studies show that certain vitamins are specially adapted for the summertime as they support the body in hot, sunny weather. A few examples:
Since the 1970s, research has shown that vitamin C (ascorbic acid) supplementation helps the body adapt physiologically to heat stress. It reduces your likelihood of developing heat-related strain and discomfort. Daily vitamin C supplementation also shortens the time it takes for your body to adjust to a new, hotter environment [12].
Vitamin E is known as a powerful antioxidant that helps skin to regenerate and maintain its healthy state.
Vitamin D is often related to skin health. Indeed, it increases the skin’s thickness, which may reduce the appearance of wrinkles. That’s one of the reasons it’s commonly found in anti-aging skincare products. Research has found that sunlight is essential for vitamin D synthesis, which, in turn, is crucial for our immune system and bone health [5].
Finally, Vitamin A (retinol) has demonstrated an anti-aging effect [13].
How to remedy sunburn
It’s important to begin treating sunburn as soon as possible. In addition to stopping further UV exposure, dermatologists recommend treating a sunburn with [10]:
- Cool baths to reduce the heat.
- Moisturizer to help ease the discomfort caused by dryness. As soon as you get out of the bathtub, gently pat yourself dry, but leaving it slightly damp. Then apply moisturizer to trap the water in your skin.
- Aspirin or ibuprofen. This can help reduce swelling, redness, and discomfort.
- Drinking extra water. A sunburn draws fluid to the skin surface and away from the rest of the body. Drinking extra water prevents dehydration.
In case of severe sunburn, do not hesitate to consult the doctor.
Sunstar and holistic health
We really hope you enjoy a safe and healthy summer —whether you're enjoying time off, engaged in outdoor work, participating in sports, or tending to your garden— and may the only thing you bring back from your holiday is a healthy smile.
Sunstar is committed to preventive health and enhancing quality of life. Our purpose and values are deeply rooted in promoting well-being, and we continue to invest in relevant research initiatives across our health food and beauty businesses.
Bibliography
[1] Treatment | NHLBI, NIH. NHLBI, NIH. 2022, https://www.nhlbi.nih.gov/health/circadian-rhythm-disorders/treatment
[2] Hoel DG, Berwick M, De Gruijl FR, Holick MF. The risks and benefits of sun exposure 2016. Dermato-Endocrinology. 2016 Jan 1;8(1):e1248325, https://doi.org/10.1080/19381980.2016.1248325
[3] INTERSUN programme. The World Health Organization, https://www.who.int/initiatives/intersun-programme/
[4] Office of Dietary Supplements - Vitamin D, https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
[5] Wacker M, Holick MF. Sunlight and vitamin D. Dermato-Endocrinology. 2013 Jan 1;5(1):51–108, https://doi.org/10.4161/derm.24494
[6] D’Orazio J, Jarrett S, Amaro-Ortiz A, Scott T. UV radiation and the skin. International Journal of Molecular Sciences. 2013 Jun 7;14(6):12222–48, https://doi.org/10.3390/ijms140612222
[7] Venosa A. 5 sneaky ways you’re being exposed to the sun’s UV rays. The Skin Cancer Foundation. 2024, https://www.skincancer.org/blog/sneaky-ways-youre-being-exposed-to-the-suns-uv-rays/
[8] Research C for DEA. Sunscreen: How to Help Protect Your Skin from the Sun. U.S. Food and Drug Administration. 2024, https://www.fda.gov/drugs/understanding-over-counter-medicines/sunscreen-how-help-protect-your-skin-sun
[9] Sharma AN, Patel BC. Laser Fitzpatrick skin type recommendations. StatPearls - NCBI Bookshelf. 2023, https://www.ncbi.nlm.nih.gov/books/NBK557626/
[10] American Academy of Dermatology Association. Sunscreen FAQs. https://www.aad.org/public/everyday-care/sun-protection/sunscreen-patients/sunscreen-faqs
[11] Harvard Health Publishing. Time for more vitamin D; 2008 Sep. https://www.health.harvard.edu/staying-healthy/time-for-more-vitamin-d
[12] Kotze HF, van der Walt WH, Rogers GG, Strydom NB. The effects of plasma ascorbic acid levels on heat acclimatization in man. J Appl Physiol Respir Environ Exerc Physiol. 1977 May;42(5):711-6. https://pubmed.ncbi.nlm.nih.gov/863837/
[13] Sachs DL, Voorhees JJ. Vitamin A: Retinoids and the Treatment of Aging Skin. In: Farris PK, editor. Cosmeceuticals and Cosmetic Practice. Wiley; 2013 Nov 22. https://doi.org/10.1002/9781118384824.ch8
Tag