LED means light-emitting diode. “It works by emitting infrared lights (causing heat) in different wavelengths/spectrums, which have different skincare benefits,” says Engelman. “Amber light stimulates collagen and elastin. Red light is most commonly used to promote circulation. White light penetrates the deepest and works to tighten and reduce inflammation. Blue light kills bacteria.”

She explains that during LED therapy, devices send light waves deep into the skin to trigger natural intracellular reactions. Depending on the light, your skin is going to respond differently. “If [the light is] red, your skin responds by building, strengthening, and maximizing cellular structure. Red light is also believed to target oil glands to reduce cytokines, which cause inflammation and play a role in chronic acne. In the case of blue light, specific wavelengths stimulate the production of oxygen radicals that kill acne bacteria, all without damaging the skin.