Summer has arrived! The days are long, and the sun is bright. As we venture into the sunny outdoors, it is important to remember that too much sun can be harmful to our skin. Wrinkles, fine lines and pigmentation changes are inevitable woes as we age. While we like to place blame on getting older, the main culprit is photoaging – severe cumulated skin damage caused by repetitive exposure to sunlight and ultraviolet light throughout our life. Photoaging is responsible for almost all or most visible changes to the skin.
Besides obvious aging signs, the sun is also responsible for inflammation associated with redness issues, capillary distention, flares of rosacea, and other inflammatory damage. Yet many people continue to bask in the sun’s rays, achieving a golden tan but also accumulating terrible damage to the skin. This is something we are all aware of. But how exactly does it happen?
How the sun affects the skin
Let us first distinguish the different types of sunrays. UV radiation is divided into three main types based on wavelength:
- UVC rays (200 – 280 nm) are the most energetic and damaging of the three rays. Fortunately, UVC is predominately filtered by the ozone layer in the stratosphere before reaching the earth’s surface.
- UVB rays (280 – 320 nm) are mainly absorbed by the epidermis but possess higher energy than UVA rays. They affect the outer layer of the skin leading to sunburns, temporary tans and pigmental shifts.
- UVA rays (320 – 400 nm) are longer rays and therefore penetrate deeper into the dermis and the precious collagen and elastin fibrils. They provide a long-lasting tan and lead to long-term changes in pigmentation. Although UVA burns only in large doses, it is now thought to be the primary type of light-related sun damage that causes the effects of photoaging. Be sure to take additional care even when at home since standard window glass will allow UVA to pass through while almost 100% of the UVB und UVC light is blocked.
Various types of DNA damage
When a harmful sunray hits the skin, it damages our genetic material, namely DNA. Located in the cell’s nucleus and bound into itself, it presents our most sensitive molecular structure. Once our genetic code has been damaged and therefore changed it leads to misinformation and long-term mutations.
Entering through epidermis and dermis, UV-radiation reaches melanocytes, that are embedded at the junction of the skin layers. Melanocytes are the cells that produce melanin giving human skin its color. Together with the natural epidermal barrier, they act as a protection shield from sunlight. A healthy skin barrier consists of 57% triglycerids, 25% wax esters, 15% squalane, 2% cholesterol ester, and 1% cholesterol.
Typically, there are between 1000 and 2000 melanocytes per square millimeter of skin. Melanocytes are besides sun influenced by hormones, antidepressants, age, free radicals, inflammation and autoimmune diseases. The melanocyte is a highly sensitive diva.
On a daily basis, each and every cell is exposed to 10’000 attacks or environmental lesions whereas UV rays make up most of this. Once hit, the DNA initiates a photochemical reaction. Depending on the degree of severity this eventually will result in a DNA break.
This in turn leads to an accumulation of senescent cells – so called ‘zombie cells’ that refuse to die, but still ‘hang around’ and release SASP (senescent associated secretory phenotype) – which compromise skin function and integrity. It also leads to an increase in matrix metalloproteinases (MMPs). These enzymes are capable of degrading all kinds of extracellular matrix proteins which induces a destruction of collagen. Elastase gets released, another enzyme that destroys elastin which is directly reflected by wrinkles and sagging skin.
The sun also damages the melanocyte and the keratinocytes which leads to an uneven spread of colour resulting in blotchy, dull and uneven pigmented skin without luster.
Safety tips
Sunburn is highly demanding in terms of DNA repair since long-term repair mechanisms are constantly overstressed. Cumulative sun damage over lifetime can lead to mutations like melanoma, basalioma and squamus cell carcinoma.
Prevention is the only way to truly save your skin. Here is what you can do:
- Use a broad-spectrum physical sunscreen rated SPF 30 or greater – every day, rain or shine, summer and winter. You get your sun damage not only when lying on the beach.
- Apply your sunscreen 15 to 30 minutes before stepping outside. Also use a lip balm with sunscreen.
- Regular reapplication is even more important than the SPF.
- Be extra careful around water and sand. These surfaces reflect the damaging rays, which can increase your chance of getting a sunburn.
- Protect your children. 80 percent of all cumulative damages occur before the age of 18.
- If possible, wear sun protective gear.
- Accessorize with a hat and a pair of sunglasses.
- Also be aware that some medications make your skin more sensitive.
- Eat smart to additionally protect your skin from the sun. Beta carotene from carrots and lycopene from tomatoes provide your skin with a certain extra degree of edible protection.
- Upgrade your car windows with a UV protection.
Chemical vs. physical sunscreen
The key difference between these types of sunscreens lies in how they block rays. Physical sunscreens use minerals (mainly titanium dioxide and zinc oxide) that sit on the surface of your skin and act as a shield reflecting the sun’s rays away. Chemical sunscreens though sink into your skin and act more like a sponge. These use ingredients that absorb and transform UV rays into heat, and release them from the body. While the UV-filtering chemicals need time to soak into your skin to form a layer of protection, physical blockers, on the other hand, start working immediately upon application.
How to minimize and repair visible sun damage
- Vitamin A (Retinol) and its many derivatives, called Retinoids, are the royalty of skincare ingredients. Retinol is one of the well-known over the counter ingredient which visibly diminishes the appearance of aging signs caused by the sun. A sufficient saturation of the cells (topically) with Retinol protects against future DNA damages. Don’t believe the old myth that Vitamin A in the sun is counterproductive. It’s not!
- Vitamin C brightens uneven skin tone. It is further assumed that the combination of sunscreen and vitamin C increases protection.
- DNA repair enzymes topically applied fix the broken DNA fragments allowing the DNA to be read properly again.
Finding a healthy balance
Let us not forget that the sun also provides a considerable array of wonderful attributes. It reduces stress, lowers blood pressure, maintains strong bones, helps keep the weight off, strengthens your immune system, fights off depression and improves your sleep.
Normally, your body creates a hormone called melatonin which is critical to helping you sleep. If we don’t get enough sunlight we don’t produce enough melatonin. This is a quite similar process to the plants’ photosynthesis. Like plants, we need sunlight as a key energy source.
While proper sunscreen use is crucial to protect your skin, you don’t have to avoid the sun completely. Enjoy life and go outside, but protect yourself, avoid midday sun, reapply sunscreen, keep an eye on your children and just don’t overdo it. As with many other things in life: it is the dose that makes the poison.
- Zürich,Dezember 16, 2022
Rittié L, Fisher GJ. Natural and sun-induced aging of human skin. Cold Spring Harb Perspect Med. 2015 Jan 5;5(1):a015370. doi: 10.1101/cshperspect.a015370. PMID: 25561721; PMCID: PMC4292080.
Kimlin MG, Guo Y. Assessing the impacts of lifetime sun exposure on skin damage and skin aging using a non-invasive method. Sci Total Environ. 2012 May 15;425:35-41. doi: 10.1016/j.scitotenv.2012.02.080. Epub 2012 Mar 28. PMID: 22459885.