How many minutes should we spend sunbathing, according to science?

With the arrival of summer, many people take the opportunity to soak up the sun and achieve that much-desired bronzed complexion. During this time of year, various health organisations warn about the risks that prolonged exposure to radiation can pose to our skin. 

Even so, some studies suggest that more people are becoming aware of these dangers and are using an appropriate sun protection factor, while also avoiding exposure during the hottest hours of the day.

Although excessive exposure is harmful, completely avoiding sunlight can also have negative effects. Getting the necessary amount of sunlight helps improve sleep quality, boosts mood, strengthens the immune system and stimulates the production of vitamin D. 

When does sunburn occur?

For a person with skin phototype III, meaning someone who tends to burn mildly and gradually develops a tan, exposure to the sun should not exceed 29 minutes during the summer. Likewise, during the winter, when less of the body's surface is exposed, this period could be extended to up to 120 minutes. 

This was the conclusion reached by a group of researchers from the Polytechnic University of Valencia (UPV) after analysing ultraviolet solar radiation between 12:30 pm and 1:30 pm. 

However, people with fairer and more sensitive skin, such as those with phototypes I and II, should take extra care, as they may experience sunburn after just 10 minutes of exposure in the case of phototype I, or 20 minutes for phototype II. By contrast, people with darker skin tones who rarely burn can tolerate between 50 and 60 minutes of sun exposure. 

The risks of vitamin D deficiency

During the winter months, it is very common for vitamin D levels to be lower, as our skin is exposed to fewer UV rays. According to the Spanish Society of Endocrinology and Nutrition, optimal levels are above 30 ng/mL, while levels between 10 and 29 ng/mL are considered insufficient, and levels below 10 ng/mL indicate a deficiency. 

In recent years, interest in vitamin D has grown significantly. Its role in health is essential, as it helps the body absorb calcium and phosphorus in the intestine. Unlike other vitamins, it also has the ability to act as a hormone. In other words, it is not absorbed solely through diet; rather, the body produces it naturally thanks to the action of sunlight on the skin. 

When levels remain low for a long time, calcium is not absorbed properly and may cause bone pain, particularly in the pelvis, spine and ribs. As a result, osteopenia and osteoporosis may develop, two conditions that affect bone density and strength. 

Furthermore, recent research suggests that alterations in vitamin D levels may be linked to certain autoimmune diseases. It has also been associated with muscle weakness and an increased risk of falls, particularly among older adults. 

Basic tips for sun exposure 

Applying sunscreen before going out in the sun is a basic requirement for protecting our skin. It is important to use high-factor sun protection products 20 to 30 minutes before sun exposure and to reapply them every two hours and after swimming in a pool or the sea. During peak sunlight hours, it is recommended to wear clothing or accessories that act as a direct barrier against the sun, such as T-shirts, caps or sunglasses.

Likewise, special care should be taken with children, as their skin is more sensitive and their immune systems are still developing. Therefore, it is important to apply sunscreen more frequently and avoid prolonged exposure, especially during periods of high UV radiation.

Ultimately, spending time in the sun can benefit our health provided it is done correctly and in line with appropriate recommendations. The most important thing is to listen to our skin, understand it and care for it by using sun protection to prevent burning or redness. If you have any concerns or notice any skin changes, it is advisable to consult a doctor to avoid future problems.