Acne light treatments were developed after extensive research into why sunlight improves acne. Because long-term sun exposure causes skin damage it is not the best answer for acne treatment. However, a certain range of light waves within the suns light was found to be effective in killing acne bacteria while being safe for skin cells. This range, 405-420 nm, is seen as a blue light and can be easily reproduced with fluorescent lamps, LEDs or dichroic filament bulbs.

When these light waves reach the skin they penetrate the acne bacteria and activate a reaction whereby singlet oxygen is released. This in turn triggers the self-destruction of the acne bacteria, rendering it non viable.

Many light treatments follow the blue light waves with the application of red light. These red light waves penetrate deeper into the skin and help to speed the healing process. This ensures that the damaged acne bacteria are quickly replaced by healthy skin cells. The red light has also been found to lessen the appearance of acne scars by activating the skins collagen cells.