Clinical Efficacy of Red Light Therapy
Hair growth and skin care: Studies have shown that red light penetrates the skin at shallow depths and stimulates follicle growth. There's evidence that the light causes vasodilation, a widening of blood vessels. "We know some hair products, such as topical minoxidil, harness that to stimulate hair growth," Rahman said.
"The dilation of blood vessels enables more blood and nutrients to reach the hair follicles. Used over multiple months consistently, red light has been shown to regrow thinning hair. But it should also be noted that when the person stops applying red light, the effects stop."
The dilation of blood vessels enables more blood and nutrients to reach the hair follicles. Used over multiple months consistently, red light has been shown to regrow thinning hair. - Dr. Zakia Rahman
Medical-grade red light therapy can be as effective as minoxidil for mild to moderate hair loss, with comparable results on hair density and growth.
Stanford Medical article