Red light therapy (RLT) is a treatment that may help skin, muscle tissue, and other parts of your body heal. It exposes you to low levels of red or near-infrared light. Infrared light is a type of energy your eyes can’t see, but your body can feel as heat. Red light is similar to infrared, but you can see it.

Red light therapy is also called low-level laser therapy (LLLT), low-power laser therapy (LPLT), and photobiomodulation (PBM).
There are many different types of red light therapy. Red light beds found at salons are said to help reduce cosmetic skin issues, like stretch marks and wrinkles. Red light therapy used in an medical setting may be used to treat more serious conditions, like psoriasis, slow-healing wounds, and even the side effects of chemotherapy.

How does red light therapy work?
Red light is thought to work by producing a biochemical effect in cells that strengthens the mitochondria. The mitochondria are the powerhouse of the cell — it’s where the cell’s energy is created. The energy-carrying molecule found in the cells of all living things is called ATP (adenosine triphosphate).

By increasing the function of the mitochondria using RLT, a cell can make more ATP. With more energy, cells can function more efficiently, rejuvenate themselves, and repair damage.

RLT is different from laser or intense pulsed light (IPL) therapies because it doesn’t cause damage to the skin surface. Laser and pulsed light therapies work by causing controlled damage to the outer layer of the skin, which then induces tissue repair. RLT bypasses this harsh step by directly stimulating regeneration of the skin. The light emitted by RLT penetrates roughly 5 millimeters below the skin’s surface.
Red light therapy devices for home use have made huge bounds in recent years. Previously, only scientists or doctors had access to red light therapy, but now everyone can use it safely and effectively —and you don’t have to leave your house to reap the benefits. Plus, you can purchase a device at a far lower price than you’d pay for red light therapy at a spa, gym, or a dermatologist’s practice.
As well as treating skin, RTL can also be used to treat hair loss. One study found that men and women with androgenetic alopecia (a genetic disorder that causes hair loss) who used an at-home RLT device for 24 weeks grew thicker hair. People in the study who used a fake RLT device didn’t get the same results.

References
1. https://www.healthline.com/health/red-light-therapy#_noHeaderPrefixedContent
2. https://www.webmd.com/skin-problems-and-treatments/red-light-therapy