Scientists are not certain how LLLT does this, but they believe it speeds up healing through more than one mechanism of action.
Firstly, red light therapy has been shown to increase the growth of cells. In a 2004 paper, researchers noted that it increased the growth of human epithelial cells 155-171%. It increased the growth of animal cells by up to 200%.
In another study, red light therapy increased the growth of fibroblasts, cells that make collagen and other substances important in healing. This could partly explain why red light therapy is effective for speeding up healing.
Another reason is that red light therapy has been shown to increase cytochrome c oxidase and upregulate genes responsible for energy production and antioxidants.
Harvard Medical School professor Dr. Michael Hamblin says there are a few different ways red light therapy is thought to work. Increased ATP, or cellular energy, production; inducement of transcription factors; and effects on reactive oxygen species, he says, result in effects such as increased oxygenation of tissues, cell growth and migration and the regulation of cytokine levels, growth factors and mediators of inflammation. All of these are important to the body’s healing processes.
Numerous studies have shown positive results for red light therapy and wound healing. For instance, a study in Photomedicine and Laser Surgery in 2009 found that red light therapy treatments with a combination of red and infrared light healed large, chronic ulcers 40% faster per month than controls. These ulcers had been resistant to other forms of treatment.
Another study, published in Lasers in Surgery and Medicine, examined the treatment of leg ulcers in diabetic patients using a combination of red and infrared light therapy. After a month of twice-weekly treatments, ulcers had healed 79%.Participants who had received a fake placebo version of the treatment had ulcers that worsened over the same month. After three months, all ulcers in the red light therapy group had healed at least 90% (most had completely healed). In contrast, only one patient in the placebo group had an ulcer that healed completely in that time.
The evidence points to the conclusion that LLLT is useful in healing wounds and injuries.