You know that the number one way to prevent skin aging is to apply sunscreen, so of course you already use a morning moisturizer with an SPF of (at least) 30. What women with gorgeous skin also do: Reapply sunscreen every few hours. Sun-shielding ingredients are only effective for about two hours—long enough to protect your skin on a morning walk or commute but not throughout the afternoon. New York City dermatologist Heidi Waldorf, MD, keeps Colorescience Sunforgettable Mineral Powder Brush SPF 30 ($50, Colorescience.com) in her bag because it's easy to brush on over makeup (and on the back of her hands or décolletage) throughout the day.
"The first time I meet someone, I immediately know if she's using a retinoid because her skin is glowy and smooth," says Miami dermatologist Leslie Baumann, MD. Retinoids are vitamin A derivatives that have been proven to boost collagen, which reduces fine lines, and to speed cell turnover, which evens out discoloration. Retinoids are available over-the-counter (as retinol) or with a prescription (as tretinoin, adapalene, and tazarotene). Because retinoids can cause some irritation at first, Hirsch recommends applying a gentle moisturizer, letting it soak in for at least 30 minutes, then applying your retinoid cream.
Salmon's high omega-3 content helps hydrate skin from the inside out and reduce the inflammation that can cause skin redness, says Baumann. And antioxidant-rich foods and drinks—blueberries, dark greens, green tea and coffee—help fight free radicals that can damage the cellular structures of the skin, accelerating skin aging.
Raising your heart rate once a day makes your skin glow. Because exercise improves your circulation and oxygen capacity, it improves your complexion. "And we know that the skin has endorphin receptors, which may also explain why it is positively impacted by aerobic exercise," says Baumann.
Cortisol, the stress hormone, ages the skin and can cause acne. Sleep reduces the cortisol level in your body. So it's a simple equation: Sleep = younger, clearer skin.