The health effects of sunlight: Part II

In my last blog post, I discussed examples of the ways sunlight affects the immune system, especially for those people with autoimmune diseases, such as multiple sclerosis. Research has shown that UV light, whether from the sun or from specialized light boxes, tamps down the inflammatory response that causes such diseases. This post is about skin, as reported in a Scientific American article called “Can Sunlight Cure Disease?” Skin is where the magic happens.

As you may have learned in school, your skin is the largest organ in your body. But you probably didn’t know that your skin is a virtual pharmacopeia. In addition to vitamin D, your skin produces melatonin, serotonin, endorphins, endocannabinoids, cortisol, oxytocin, leptin, nitric oxide, cis-urocanic acid, itaconate, lumisterol, tachysterol, and a dozen other vitamin D-like compounds that don’t even have names yet. To keep you healthy, your skin is in constant conversation with the rest of your body, including your brain. It’s also a major site for the immune system. As such, it is stocked with body-defending T-cells, macrophages, neutrophils, cytokines, antimicrobial peptides, and other key players. Sometimes these “key players” go haywire, as with auto-immune diseases.

UV light stirs up this stew of cells in lots of complicated ways, such as breaking chemical bonds, producing multiple molecules, increasing protein production, flipping atoms to new configurations, producing lipids, and so forth. No one fully understands how all of this works—how all the cells and signals bounce off one another. But they do know that UV light “has a surprising ability to calm an immune system that has bolted out of control.” They know that UV light triggers a cascade of signals that reach every organ in the body, and they’re tracking the way molecules in the skin respond to UV light. They’d like to discover a pill that will tamp down an out-of-control immune system. For now, there’s just sunlight or a light box.

I get plenty of sun and my immune system has kept me healthy. But my skin is a mess.

For an introduction to this blog, see I Just Say No; for a list of blog topics, click the Topics tab.