Red light therapy, sometimes called photobiomodulation, applies specific wavelengths of light (usually around 630 nanometers) onto your skin. These wavelengths can penetrate two to three millimeters below the skin, and cause positive reactions in the cells just under your skin, says Dr. Apple Bodemer, a board-certified dermatologist and professor at the University of Wisconsin School of Medicine and Public Health.
There aren’t a lot of high-quality scientific studies available, and many of the red light therapy studies are funded by companies that make red light products, which should be taken with a grain of salt, says Bodemer. But there seems to be enough evidence that red light therapy may be helpful for some people, she says.