When we expose our skin to the sun's rays, we can achieve both positive and negative effects. Most people have probably heard that vitamin D and sunlight go together.
The sun stimulates the production of vitamin D in our skin, which has many important functions, including vitamin D, which is needed for our bones and teeth and for the immune system. It can also make us feel more alert and happy. Since the body itself cannot produce vitamin D, it is important that we get a sufficient dose in other ways, such as through the sun and diet. But overexposure to the sun can, on the other hand, cause damage to the skin.
So what happens to the skin when it is exposed to the sun?
When we stay in the sun's rays, the skin absorbs the ultraviolet light (UV) that comes from the sun. This can lead to visible damage to the skin such as premature ageing, hyperpigmentation, sun eczema but can also go deeper and cause DNA damage at the cellular level which can lead to aknitic keratosis (superficial skin changes, often scaly patches) and skin cancer.
UV light is divided into 3 variants, UVA, UVB and UVC. UVC does not reach the earth's surface as we are protected by the ozone layer, so it is UVA and UVB that we must protect ourselves against.
- UVA is the rays that UV light mostly consists of. These rays penetrate deep into the skin and contribute to premature aging of the skin. They stimulate the production of free radicals that can cause premature aging with dryness, hyperpigmentation, wrinkles and sagging skin.
- UVB cannot penetrate as deeply into the skin as UVA but can cause more acute damage, such as burning. It is also UVB that increases the amount of pigment in the skin and makes us tan. UVB is absorbed by the DNA in the skin cells and can cause damage that can lead to skin cancer. But UVA can also cause skin cancer. It is also UVB that starts the production of vitamin D in the skin.
How do we then take part in the positive but avoid the negative?
It is usually said that on a Swedish summer day it is enough to expose the skin to the sun for about 10-15 minutes to replenish the daily requirement of vitamin D. Light skin needs less time than dark skin because darker skin filters out more UV radiation than light skin does. When you have filled up the daily requirement, you can say that the skin "shuts down" that function and only the negative effects remain.
Using sunscreen is therefore essential to protect your skin from harmful UV radiation. Remember to reapply during the day to get long-lasting protection and feel free to take a siesta in the middle of the day!