Many people find sunbathing relaxing and enjoyable, and they love the darkening effect on their skin known as tanning. The beneficial psychological effects of sun exposure are well-documented, as are its harmful effects, including skin cancer development. But many people do not understand that the tan that results from sun exposure is actually the skin’s way to protect itself from additional damage and ultimately, it’s loss of function, including protection from injury.
When sunlight strikes your skin, either just because you are walking outside for a few minutes or intentionally sunbathing to get a tan, the skin cells in your epidermis, called keratinocytes, are damaged, causing a number of responses to occur. The little “brains” inside each skin cell, called nuclei, really don’t like ultraviolet light, which are some of the sun’s harmful rays, and they send out signals to other cells called melanocytes, telling them to make some more protective pigment to shield the skin cells from further damage. The melanocytes deposit the pigment on the top of the nuclei of the skin cells, on the side facing the sun, to cover the nuclei like a hat. These are called melanin caps. Melanin, the pigment that provides the tan color to your skin, absorbs the harmful ultraviolet rays, protecting the nuclei from further damage. So while additional damage may be minimized, the initial damage has been done, and the cells will then do their best to repair the damage and prevent the development of skin cancer.
Unfortunately, the rest of the skin cell outside the nucleus is also damaged by the sun, as are the cells in the deeper parts of the skin called the dermis. When damage occurs here, the cells gradually lose their ability to make other important molecules like collagen, which is important in maintaining the structural integrity of the skin. Collagen provides protection and support to the blood vessels and nerves, and anchors the epidermis to the dermis. As the sun damages the skin gradually during the course of life, the skin’s integrity becomes compromised, and you begin to see bruises and skin tears with milder injuries. All of these changes are largely irreversible.
So, while tanning may feel good and “healthy”, the damage caused by both acute sunburn and chronic low grade exposure is not particularly healthy.