Why the sun makes us both healthier – and sicker
Spending time in the sun can make us both healthier and happier. But too much as well as too little sun can cause serious health problems. How much sun is right for you depends, among other things, on your genes, how much pigment you have, and where in the world you are.
"We need to find a balance. I think we should continue to enjoy the sun in moderation – that is often good for us. But anyone who spends a lot of time outdoors needs to protect themselves from the sun’s UV rays, otherwise the risk of serious skin cancer increases," says Kari Nielsen, a dermatologist at Skåne University Hospital and a researcher in dermatology at Lund University.
A common form of cancer
Every year, around 100,000 people in Sweden are diagnosed with some form of skin cancer. Skin cancer is mainly caused by UVB rays, which give us sunburn and produce vitamin D, but also cause direct DNA damage in the skin. UVA rays are not as strong, but they penetrate deeper into the skin and cause wrinkles, pigmentation spots, sun eczema and indirect damage that makes the skin age faster and can lead to skin cancer. But what about the positives? Why do we actually feel good in the sun? One explanation is that the sun’s UVB rays contribute to the production of vitamin D. The sun vitamin is an important part of our bone health and calcium absorption, while also strengthening our immune system and general health. Sunlight on the skin can also release nitric oxide into the blood, which can lower blood pressure and have a positive effect on cardiovascular health.
"We also know that sunlight releases endorphins that increase feelings of happiness and relaxation. For many people, spending time in the sun is a natural way to improve mood and reduce stress," says Kari Nielsen.
At the same time, however, high exposure to the sun’s ultraviolet rays can cause skin cancer. Australia has the highest number of cases of serious skin cancer in the world, but Sweden is also high on that list.
UV apps are a cause for concern
Behind the high numbers is a combination of fair skin type, high UV exposure and a tendency to spend more time in the sun than the skin can handle, observes Kari Nielsen. She is also concerned about UV apps that have become popular among young people who want to maximise their sun exposure when the UV index is high instead of protecting themselves from the sun at those times.
It’s a serious trend. Many young people find it difficult to see the consequences that excessive sunbathing can have later in life.
She also thinks the ban on tanning beds for children under 18 is good, but would prefer a total ban.
"In Australia, tanning beds have been banned completely, and in the Nordic countries, with almost equally high skin cancer rates, we should follow suit. What makes tanning beds dangerous is that they expose the entire body intensively, both front and back, to strong UV light. Outdoors, we expose only some parts of the skin at a time," says Kari Nielsen.
Text: Monne Ljungberg
Photo: Roger Lundholm
The article was previously published in the journal Vetenskap & Hälsa, 2026.
How the skin handles the rays
The sun also affects several common skin problems. Excessive sun exposure makes the skin age faster and gives us more wrinkles. At the same time, some skin problems improve in the sun, while others get worse.
1. Rosacea
Also known as adult acne. Causes acne-like breakouts or troublesome skin redness. Symptoms in sensitive skin may worsen during the summer when blood vessels dilate because of sun and heat, which is why the right sun protection is important.
2. Sun spots, age spots or lentigo solaris
Unlike moles, pigmentation spots are caused by too much sun exposure. The spots are a sign that the skin, mainly on the face and backs of the hands, has been exposed to strong UV radiation for a long time. Prevent them by moderating sun exposure.
3. Melasma
A common pigmentation disorder in the form of brown patches on the face. The cause includes hormonal fluctuations during pregnancy, contraceptive pills and menopause medication in combination with sunlight. Anyone taking hormone-affecting medication or who is pregnant should therefore also use effective sun protection.
4. Actinic keratoses
Reddish, often flaky and recurring cell changes in the outer layer of the skin that signal chronic sun exposure on exposed parts of the body such as the face and backs of the hands. They can be prevented and may regress if sun protection is improved. A doctor decides whether the keratoses should be treated.
Best tips if you want to enjoy the sun!
- Learn how sensitive your own skin is and adapt to that, not to trends. Use the online service, "Min soltid", to estimate how long you can stay in the sun without getting burned.
- Also learn to use the UV index shown in many weather apps. When the index is above three, you need to protect yourself against sunburn.
- If you use sunscreen, it should have at least SPF 30 in order to provide some protection against UVA as well. For the protection to work, you need to apply it generously and often.