The red light- wavelength of 620 - 660 nanometers
The red light will motivate the blood circulation in the light-positioned area and stimulate metabolism. This results in oxygen and nutrients will be carried to hair follicles effectively. It also stimulates ATP production (Adenosine Triphosphate), an organic compound and hydrotrope providing energy to drive many processes in living cells. Moreover, the red light also stimulates metabolism of hair follicles to function normally that leads to boosted keratin production and increasing new hair.
Although we get these lights naturally from the sun, the sunlight has ultraviolet A and ultraviolet B (UVA and UVB) rays that can damage our hair and skin. LED light is a safer technique for you.