After a sunburn, a thin layer of skin may flake or peel off from the damaged area. The peeling usually starts a few days after a sunburn and may continue for about a week. While a sunburn itself is painful, the peeling of the skin is not. It is a sign, however, that significant skin damage has occurred and is in the process of healing.
Radiation Damage From the Sun
The sun emits ultraviolet radiation, often called UV radiation. Depending on a person's total exposure time to the sun and baseline skin color, this type of radiation damages exposed skin cells. In some instances, the top layer of skin responds to UV radiation by becoming darker and thicker in a protective response. However, UV radiation can cause harsher skin damage, killing the exposed skin cells and producing a sunburn reaction. Sunburned skin appears red and is typically painful.
The area damaged by UV radiation heals by forming a fresh new layer of skin to replace the dead skin layer. Underneath the sunburned skin, new skin cells form to replace the sun-damaged skin. The new layer typically takes about 4 to 7 days to fully form. Throughout the process of formation, the new skin layer is delicate, and thus remains shielded by the intact dead outer layer of sunburned skin.
When the freshly formed skin cells mature to the point of becoming resilient enough to function as the outer layer of skin, peeling of the dead outer skin layer occurs. Sloughing of the dead skin occurs gradually. If you peel the dead skin before it comes off on its own, you may expose a new layer that is still delicate and fragile, triggering tenderness or bleeding.
After the new skin layer is completely formed and the dead skin peels off, the discoloration of the skin, a tan, may remain for weeks to months. The dark coloring gradually fades away, a sign that the skin is refreshed and all of the skin cells directly affected by UV radiation have been replaced. However, sun exposure often causes imperceptible damage to the genetic material, or DNA, of the skin cells. In this way, even skin cells produced years after a sunburn may carry damage that can result in problems such as aged appearance of skin or cancer.
- The British Journal of Dermatology: Variations in Skin Colour and the Biological Consequences of Ultraviolet Radiation Exposure
- Proceedings of the National Academy of Sciences of the United States of America: UV Light Phototransduction Activates Transient Receptor Potential A1 Ion Channels in Human Melanocytes
- International Journal of Molecular Sciences: Vitamin D and Death by Sunshine
- VisualDx: Essential Adult Dermatology; Noah Craft, M.D., Ph.D., et al. (eds.)