Sun exposure is often framed as something to avoid at all costs, yet emerging research suggests the story is more nuanced. From vitamin D production and circadian health to skin cancer risk, how—and when—we are exposed to the sun matters.
The new science of sun exposure
According to Jen Newell, ND, owner/founder of Connected Health & Skin, a holistic skincare clinic in Toronto, the conversation around sun exposure has become very polarized.
“On one end, there’s the message that the sun is dangerous and should be avoided. On the other end, there’s messaging that sunscreen is dangerous and the sun should be embraced without limits,” says Newell. “The truth, as usual in medicine, sits somewhere in the middle.”
In fact, since the 1900s, we’ve been implored to avoid the sun and its inherent dangers.
But in the 2000s, research started to reveal that the benefits of safe sun exposure were much more plentiful than initially realized:
- helps support the immune system
- may lower the risk of severity of diseases such as multiple sclerosis (MS), childhood eczema, COVID-19, and other autoimmune conditions
- and may have cardiovascular benefits
The balance between vitamin D synthesis and skin cancer risk
“Sunlight plays an essential role in human physiology,” says Newell.
Exposure to ultraviolet (UV) radiation triggers the skin to produce vitamin D, which acts more like a hormone than a vitamin, she explains. Vitamin D is involved in immune regulation, bone health, metabolic function, and even skin barrier integrity.
However, cautions Newell, excessive and cumulative ultraviolet exposure, especially when it leads to sunburn, is clearly associated with skin damage; premature signs of aging; and increased risk of skin cancers, such as melanoma, basal cell carcinoma, and squamous cell carcinoma.
“For many people, short periods of intentional sun exposure can support vitamin D production without significantly increasing risk,” says Newell.
It’s critical to understand that people’s sun needs and risks vary, depending on a number of factors including:
- Skin pigmentation: This protects the skin from damage from UV rays but also reduces vitamin D synthesis.
- Geography: The further you live from the equator, the lower the sun exposure and the more often you may experience vitamin D deficiency.
- Altitude: UV radiation increases with altitude—for instance, the UV index in Edmonton is less than that of the top of a mountain in Jasper.
- Genetics: More than 2,000 genes have been linked with skin cancer.
- Reflection from snow, water, and light-coloured sand: This can increase your UV exposure.
Time of day also dictates the sun’s effects.
Midday sun between 10 am and 4 pm is when the sun’s rays are strongest. Limited time in the sun is recommended during that time frame even in winter and especially at higher altitudes.
Soaking up the morning light produces unique benefits.
Sunlight absorbed before 10 am results in earlier sleep timing, earlier midpoint of sleep, and better sleep quality. Morning sun may also help speed up metabolism and may effectively reduce obesity.
Foods that support UV defence
What you put inside your body can help preserve your outer layer, too!
Antioxidants provide powerful protective support from the skin’s aging process brought about by exposure to UV radiation. For instance:
- Green tea extract—which is full of polyphenols—is considered a potent nutrient for skin protection.
- Retinol, a derivative of vitamin A, is critical for skin cell regeneration and skin integrity; find it in products such as cheese, eggs, oily fish, and yogurt.
- Vitamin C (found in citrus fruits, peppers, strawberries, and broccoli) contains photoprotective ingredients, while Vitamin E (found in plant oils, nuts and seeds, and wheatgerm) helps to repair damaged skin cells.
Sunscreen decoded
There are two types of sunscreens. Mineral sunscreens, also called physical sunscreens, sit on the surface of your skin, shielding it from the sun; they contain active ingredients zinc oxide or titanium dioxide. Chemical sunscreens act like a sponge; they absorb the sun’s rays and convert the UV light into heat, which then disperses. Several ingredients in some chemical sunscreens may endanger marine life. These include oxybenzone, octinoxate, and octocrylene. They may accumulate in tissues of coral, inducing bleaching and deformation. In green algae, they can impair growth and photosynthesis.
It’s not enough to select your sunscreens based on labels such as “reef-safe,” “reef-friendly,” “hormone-safe,” and “kid-safe.” For one, there is no regulated or set meaning behind the labelling. In addition, the science of what is or is not safe is an evolving area of study. Savvy consumers should heed the guidance of organizations such as the Environmental Working Group for lists of ingredients and reviews instead of deferring to marketing gimmicks.
According to Newell, you should use roughly the volume of a shot glass (about 1 ounce [30 mL]) of sunscreen to cover your entire body.
When it comes to your face, ears, and neck, use 1 teaspoon (5 mL). Don’t forget to apply sunscreen to your lips using a lip balm or stick with a sun protection factor (SPF) of 30 or higher.
“Multiple studies show that most people apply only 25 to 50 percent of the recommended amount,” says Newell. “When sunscreen is applied too thinly, the protection drops dramatically.”
SPF myths
Some SPF myths just won’t die. Here’s what the research actually says.
Myth: A base tan prevents sunburn. This myth is still widely spread on social media. In reality, there is zero evidence that a base tan is protective against sunburn or cancer risks from sun exposure.
Myth: SPF 100 offers double the protection of SPF 50. When properly applied, SPF 50 sunscreen blocks 98 percent of UVB rays, while SPF 100 blocks 99 percent. No sunscreen can block 100 per cent of the sun’s UVB rays. When used correctly, sunscreen with SPF values between 30 and 50 offers adequate sunburn protection, according to the EWG. And no matter which number you choose, you still have to reapply it every two hours—a higher SPF value doesn’t equal a longer lasting formula!
Myth: Natural sunscreens don’t look as good or work as well as conventional sunscreens. Earlier formulations of natural sunscreens used to leave a thick, white cast. Now, even sunscreens that blend into darker-toned skin are available.
Myth: You can’t protect your skin without harming the coral reefs. Strong evidence suggests that some ingredients in chemical sunscreen, especially oxybenzone, are harmful to corals if the concentration in water is high. Mineral sunscreen includes ingredients with reduced impacts on aquatic organisms, while ultraviolet-protection-factor clothing can also protect your skin from the sun.
How to reapply SPF over makeup
A step-by-step guide from Dr. Jen Newell, ND
- Start with a strong base layer in the morning
- Sunscreen should be applied as the final step of skin care and before makeup. This ensures it forms an even, protective film on the skin. This order matters because sunscreen needs to sit directly on the skin to form a consistent UV-filtering layer.
- Plan to reapply every 2 hours with significant or sustained sun exposure. Sweat, oil production, and normal facial movement gradually break down the protective film.
- How to reapply over makeup:
- Before adding more product, gently blot the skin with blotting paper or a tissue to remove excess oil and sweat.
- Choose the right SPF format (some sunscreen textures are far easier to apply over makeup than others). SPF sprays as well as powdered sunscreens and sticks or cushions may be much easier to reapply than many creams.
- Apply using pressing motions. Press or tap the product into the skin with a dense brush or sponge to avoid disturbing makeup.
- Focus on high-exposure zones. Prioritize areas that receive the most sun exposure, such as the nose, cheeks, forehead, ears, lips, and cheekbones.
- Have realistic expectations. Morning sunscreen provides the foundation of protection. Midday SPF reapplication helps maintain it.
Sun exposure during cancer treatment
Some chemotherapy drugs can make your skin more sensitive to the sun, a phenomenon known as photosensitivity. This sensitivity can continue months after treatment is over, so it’s especially important to protect yourself from the sun during this time.
During radiation therapy, keep the treated area covered to protect it from sun exposure. After treatment ends, apply a broad-spectrum sunscreen with SPF 30 or higher, as the skin may remain more sensitive and prone to burning.
This article was originally published in the July 2026 issue of alive magazine.
