We need sunlight. The light helps to maintain our sleep-wake cycle (biological clock) and sunshine puts us in a better mood. It makes us want to go outside more, which means we take more physical exercise. More exercise is good for your health.
When exposed to UV radiation, our skin produces vitamin D. We need vitamin D for healthy teeth, bones and muscles. Vitamin D is also good for our immune system. A healthy immune system makes us less likely to become ill.
On average throughout the year, the sun is our main (and practically our only) source of vitamin D. The sun is low from October through March, so our bodies do not produce vitamin D during this period. That is why people often need to consume vitamin D in other ways in the autumn and winter, for example by eating foods that contain vitamin D (such as fatty fish) or by taking vitamin D in the form of nutritional supplements. How much vitamin D an individual needs varies greatly from person to person.
UV radiation can also be bad for your health
We need sunlight, but too much of it is bad. The UV radiation in sunlight can burn your skin. Over time, UV-A radiation causes your skin to age more rapidly. If your skin gets burnt badly and often, the damage that occurs can cause skin cancer later in life. Too much sunlight can also severely damage your eyes.
If you stay in the sun for too long, you will get sunburnt. In the Netherlands, this can happen within 20 minutes. How quickly this occurs depends on factors such as the UV index, your skin type and your age. Dark skin burns less easily than light skin. If you have a sunburn, your skin will be red and sore and you may get blisters. This can last for days. After that, your skin will peel.
UV radiation damages your skin. For the most part the skin heals on its own, but this is not always the case. The more often and the more severely you get sunburnt, the more your skin will become damaged beyond repair. In the long term, this damage can lead to skin cancer. Since the Netherlands Comprehensive Cancer Organisation (IKNL) started keeping a record of cancer patients in the Netherlands Cancer Registry (NKR) in 1990, the number of people who develop skin cancer has risen sharply. This is mainly due to the fact that people live longer. Although young people can also get skin cancer, it is a disease of old age. The exact cause of the rest of the increase in skin cancer cases is not yet clear. It is likely a combination of changing sun-exposure behaviour and changing skin sensitivity.
Because people live longer, it is even more important that they protect themselves against UV radiation from a young age. People under the age of 25 who regularly get sunburnt are at a higher risk of developing skin cancer later in life. It is therefore important to ensure adequate sun protection for children (and young people) in particular.
UV radiation damages the lens of the eye. When this happens, the lens no longer works properly, which causes blurry vision. This damage accumulates throughout life, just like skin damage. Too much radiation can also lead to ‘snow blindness’. This happens when the cornea of your eye becomes inflamed, a condition known as keratitis. In the long term, you can get cataracts or even go blind.