iGlow Hair Gel is chemo-luminescent, meaning that a chemical reaction on your hair will let you create your own light without black lights. Don't worry, the website says its safe, "While iGlow is classified as a "temporary hair color" it does not actually color the hair cuticle. It "coats" the hair with color. The gel is the delivery medium for the luminescence (glow). As such it is safe for color-treated or bleached hair when used as directed."