The exact benefits of LED light therapy vary, depending on the wavelength used:
Red and infrared lights increase circulation, reduce inflammation, and allow for better topical product absorption. As the epidermis absorbs the light, it stimulates the fibroblasts that produce collagen to help treat fine lines and wrinkles and give skin a more plumped, smooth appearance.
Blue light treats acne by destroying the bacteria that causes it. It penetrates down to the skin's sebaceous glands to kill bacteria from the inside out. Blue light for mild to moderate acne is often used in conjunction with red light, which is effective at reducing inflammation and redness due to the increase in oxygen and circulation.
The American Academy of Dermatology (AAD) recommends LED light therapy to decrease acne-causing bacteria.