“Very. Cleansing is especially important if you wear makeup. Leaving mascara and eye shadow on overnight can contribute to eyelid infections and inflammation. Use a gentle cleanser that contains synthetic detergents called syndets — for example, Cetaphil or CeraVe — before applying moisturizer or any antiaging products you use. But even if you don’t use makeup, the average person is exposed to dust and other particles that can clog pores and oil glands, contribute to acne, and form a layer that prevents moisturizers from penetrating. Some of these substances contain free radicals, unstable atoms or molecules that can damage collagen and elastin and contribute to wrinkles and aging.” — Aleksandar L. Krunic, dermatologist at Swedish Covenant Hospital