Sunburn is a common consequence of sun exposure, causing intense redness and pain. A potential approach for relief and faster recovery involves Red Light Therapy (RLT), which utilizes specific near-infrared and red wavelengths. This article investigates the science behind using RLT, a treatment known as photobiomodulation, to determine its validity for soothing and healing acute sunburn.
Understanding Sunburn at the Cellular Level
Sunburn is fundamentally a radiation burn caused by ultraviolet (UV) light penetrating the outer layers of the skin. The UV rays directly damage the DNA within the skin’s primary cells, called keratinocytes, which form the protective barrier. This cellular injury triggers a protective, self-destruct mechanism known as apoptosis, leading to the formation of “sunburn cells.”
The skin recognizes this widespread cellular damage as a threat, initiating a powerful inflammatory cascade. Injured keratinocytes release various chemical messengers, including pro-inflammatory cytokines, which signal the immune system. These signals cause vasodilation, an expansion of blood vessels, resulting in the visible heat, swelling, and characteristic redness associated with a burn. The pain is a direct result of these inflammatory mediators sensitizing nerve endings in the damaged tissue.
The Mechanism: How Red Light Interacts with Damaged Skin
Red Light Therapy operates through photobiomodulation (PBM), which uses non-thermal light to stimulate biological activity. The light source typically emits red light (630 to 660 nanometers) and near-infrared light (810 to 850 nanometers). These specific, longer wavelengths are able to penetrate the skin’s surface and reach the underlying damaged cells.
Once inside the cells, the light is absorbed by light-sensitive molecules known as chromophores, most significantly Cytochrome C Oxidase, a protein found in the mitochondria. Light absorption at this level stimulates the electron transport chain, which results in a measurable increase in the production of Adenosine Triphosphate (ATP).
ATP is the primary energy currency of the cell, and its increased availability provides the necessary resources for damaged cells to accelerate their repair processes. This enhanced cellular energy helps the keratinocytes recover from the UV-induced stress and DNA damage. The PBM process helps to reduce oxidative stress, which is a major contributor to inflammation. By modulating the inflammatory response, RLT can help to dampen the overreaction of the immune system. It works to inhibit pro-inflammatory cytokines that cause much of the acute pain and swelling, creating a more favorable environment for tissue regeneration.
Clinical Evidence and Efficacy for Acute Sunburn
Scientific investigation supports the use of RLT as a supplementary treatment for acute, first-degree sunburns. Clinical studies have demonstrated that exposing sunburned skin to red light results in a significant reduction in symptoms such as burning, redness, and swelling. This improvement is often noticeable within the first few days of treatment.
The therapy’s ability to accelerate skin repair is a primary benefit, with research indicating that RLT can speed up the healing process by up to 50% compared to untreated burns. This faster healing is linked to the light’s anti-inflammatory effects and its promotion of cellular recovery. By reducing the severity of the inflammatory reaction, RLT helps the skin transition more quickly out of the acute phase of injury.
The treatment reduces specific markers of sun damage within 24 hours of application. For instance, the expression of MMP-1, an enzyme that breaks down collagen and is elevated after UV exposure, drops following RLT. This suggests a direct biological intervention in the skin’s response to radiation damage.
Some research has explored the application of RLT before sun exposure, suggesting a protective effect equivalent to a low-level sunscreen. While RLT does not block UV radiation, this pre-treatment may increase the skin’s resilience to UV stress. Overall, the evidence confirms RLT’s role in accelerating recovery, reducing pain, and minimizing the visible signs of a mild to moderate burn.
Safe Application and Crucial Precautions
The correct application protocol is paramount to ensure safety and effectiveness. It is generally recommended to use devices that emit both red light (630–660 nm) and near-infrared light (810–850 nm) for the best results, as these wavelengths offer targeted and deep penetration. The device should be positioned 6 to 12 inches away from the affected area to allow for proper light coverage.
Each treatment session should last between 10 and 20 minutes, with a frequency of two to three times per week for acute burns. Users must avoid applying RLT immediately after sun exposure while the skin is still intensely hot and tender. Users should wait for the initial acute heat to subside before beginning treatment.
RLT should never be applied to severe sunburns characterized by blistering, open wounds, or second-degree damage, as these require professional medical attention. Individuals who are taking photosensitizing medications, which increase skin sensitivity to light, should consult a healthcare provider before starting RLT. Always use eye protection designed for light therapy during sessions.