Red light therapy—a treatment harnessing a specific form of energy that penetrates the top layers of skin—is marketed for skincare and wellness, but has its roots in NASA research investigating if this type of light can promote plant growth in space.

Findings

Additional insights we found via Health vs. Hype

Red light refers to light at 630 to 700 nanometers, which penetrates the top layers of skin, but does not penetrate deeper.
A dermatologist interviewed on this podcast produced by the American Medical Association explains that when red light hits the skin, it can improve mitochondrial efficiency to boost energy, reduce inflammation, and release a substance called nitric oxide, which helps dilate blood vessels. It may also help activate genes that produce collagen and elastin, potentially promoting skin health.
Much of the research on red light therapy has focused on treating a painful side effect of chemotherapy called mucositis which is mouth inflammation. Red light therapy has been shown to help alleviate that symptom. Red light therapy may not work for other inflammatory conditions, such as psoriasis or arthritis, and research on broader inflammation applications remains limited.
Red light therapy masks won't penetrate deep enough to address joint inflammation or nervous system issues.
Blue light, which targets the very top layer of the skin, targets molecules that are made by the bacteria that cause acne on the skin, called porphyrins. The light helps produce substances toxic to the bacteria, thereby reducing acne.
Small studies suggest red light may also help treat acne, but rigorous studies are lacking.