Q: If antioxidants help prevent and repair environmental damage to the skin, should I put them on in the morning before I go outside, at night, or both?
A: Antioxidants extinguish free radicals, the unstable oxygen molecules (generated by exposure to UV rays and pollutants) that kill off collagen. Free radicals are also released when the immune system repairs damaged skin cells, and “the chemical reactions involved in this healing process can be a more powerful producer of free radicals than sun or cigarette smoke,” says dermatologist Ellen Marmur of Marmur Medical in NYC. “Because repair happens as you sleep, it’s optimal to apply a serum or cream with antioxidants like resveratrol, green tea, or vitamin C at night,” she adds. “Most daytime moisturizers with sunscreen already help neutralize toxic radicals from UV exposure, so there’s no need to add more.” Not to mention that vitamin C, one of the strongest and most prevalent free-radical fighters, is deactivated when exposed to light and air.