Recent studies have indicated that sunlight exposure may have immunomodulatory effects and protect against infections, including acute respiratory infections such as influenza.[i]
Additionally, studies have shown that high levels of solar ultraviolet radiation (UVR) exposure are associated with lowered rates of allergies, autoimmune diseases and cancers.[ii],[iii] While these results are often attributed to increases in vitamin D, researchers have now demonstrated that sunlight exposure can improve immune function by improving the motility of killer T-cells.
In addition to these findings, researchers also point out that infectious outbreaks, including influenza, tend to happen more often during winter months when many people have little to no sunlight and UVR exposure.
Additional research from Columbia University suggests that UV light can kill even drug-resistant bacteria without inducing skin damage.[iv] Researchers believe there are two main facets that explain sunlight exposure’s effect on immune function: