9 Beauty Fails That Mess With Your Skin (and How to Fix Them)

1. Staying up past midnight.

What's the big deal? Late-night partying — or just blowing through your Netflix queue — causes more than dark circles. A recent study noted sleep-deprived women (those who fall into the "poor" category of the Pittsburgh Sleep Quality Index) age faster than those who catch enough Zs. The theory: Skin-repair rates lag with less sleep, causing lines, spots, and slack skin.

The fix: Studies show the antioxidant resveratrol, found in grapes and red wine (and in Chanel's serum, here) not only amps up skin's ability to mend itself but also gets your body to create its own antioxidants, says NYC derm Joshua Zeichner, M.D. Apply at night, when skin is in repair mode.

2. Owning the urban jungle.

What's the big deal? Smog is hell on skin, thanks to a toxic duo of ozone (a noxious gas created when fumes, like car exhaust, mingle with sunlight) and particulate matter (bits of soot and liquid drops of acids and chemicals that float in the air). The first destroys lipids and proteins, causing irritation and breakouts; the latter, ranging in size from about 2.5 to 10 micrometers (one-seventh the width of a hair), "gets into pores, where it spurs inflammation and free radicals, leading to spots and lines," says dermatologist Fredric Brandt, M.D. In fact, a study found women who lived in high-traffic areas had 20 percent more pigmentation.

The fix:Give smog a p.m. smackdown with a high-tech cleansing brush, says derm Jeannette Graf, M.D. In a clinical test against particulate matter, Clarisonic's (here), with its oscillating bristles that move 300 times per second, cleared pores 30 times better than hands.

3. Blowing off a cardio session.

What's the big deal?Exercise can keep you looking younger longer. One study shows that those who get sweaty on the reg (at least 14 minutes per day) have longer telomeres — protective bumpers on the ends of our DNA strands, which naturally shorten over time. Researchers believe that if you can delay this shortening process, you may delay the signs of aging.

The fix:The closest thing to a workout-in-a-bottle: Telo-5, a new antiaging system (used in Kate Somerville's cream, above) based on Nobel Prize-winning research on telomere preservation, and Juvenessence, a peptide technology (find it in Dr. Brandt Do Not Age Time Reversing Cream, $130, Sephora.com). Topical DNA-repair enzymes like plankton (found in Neova DNA Total Repair, $99, Neova.com) might also be key. "In theory, they should be able to repair telomeres along with other DNA," says Dr. Zeichner.

4. Loving cocktail o'clock.

What's the big deal?More than two drinks can be a buzzkill for skin. Alcohol creates free radicals and ups inflammation. It's also a diuretic and a vasodilator, leaving skin dry, puffy, and flushed. Social smoker? You'll likely wake up to a washed-out or grayish skin tone. "Just one cigarette drastically reduces the oxygen levels in your skin, hindering circulation," says Dr. Graf.

The fix: A cocktail of super-potent extracts and antioxidants will neutralize free radicals before they can do damage. Also, in the a.m., pop an anti-inflammatory ibuprofen to reduce the flush in your face, says Dr. Brandt. To help skin rebound from smoke-induced oxygen loss, reach for a serum rich in saccharomyces lysate, a yeast extract that helps restore cell respiratory function, says Dr. Graf.

5. Driving without protection.

What's the big deal? Unless you have seriously tinted windows, UVA rays — responsible for lines, pigmentation, and all three types of skin cancer — can penetrate glass and damage skin cells year-round, explains Dr. Zeichner. Studies show that both sun-induced skin damage (like wrinkles and spots) and skin cancers appear more on the left (or driver's) side of our faces.

The fix:When it comes to UV damage, nothing defends like sunscreen. Titanium dioxide-based blocks (like the one at left) start deflecting rays the second they're applied. (Chemical sunscreens, on the other hand, require 15 minutes to soak into skin — not ideal if you tend to run late in the morning.) Remember: Any form of SPF needs to be reapplied every two hours, so tote a mini in your purse (not in your car though — high temps can deactivate the ingredients in the formula) and apply before your ride home.

6. Busting your ass at work.

What's the big deal? Fingers crossed, your killer work ethic will soon land you a fat promotion and raise, but all that day-to-day stress can lead to breakouts. Stress triggers the production of androgens — a hormone proven to increase oil production, which leads to clogged pores, says Dr. Brandt.

The fix: Before bed, wash with a cleanser made of 2 percent salicylic acid (new and amazing: Olay Fresh Effects Clear Skin Acne Hater Deep Scrub, $7, drugstores), letting it absorb like a mask for three minutes. The next day, apply a lotion with less potent, but still effective, levels of the ingredient (like Lancôme's, below, which also mattifies shine). If you need to up the ante, your derm can prescribe the Pill (like Yaz) or an anti-androgen med to balance hormones.

7. Gulping down green juice.

What's the big deal? ODing on antioxidant-rich veggies can be healthy for skin — unless they're all you're ingesting. "A multiday cleanse deprives skin of oils rich in essential and omega fatty acids, found at high levels in foods such as salmon and nuts," says Dr. Brandt. Depriving yourself, even just for a few days, can lead to noticeably dull, dehydrated skin.

The fix:Get back your glow with a fatty-acid-packed moisturizer. The most effective ingredient, according to derms: ceramides (in the Algenist oil above), which naturally cushion our skin cells in the outermost layer of skin. "When deposited topically, they act as powerful emollients, restoring hydration and luminosity," says Dr. Brandt.

8. Basking in the heat.

What's the big deal? Whether you're in the sun or not, "heat alone is enough to trigger brown spots," says Dr. Brandt. High temps — anything above 90 degrees — spur inflammation and free radicals (oxygen molecules that mess with normal cell function), kicking pigment-making melanocyte cells into overdrive.

The fix: Stop the skin damage before it can even start. Ingredients such as kojic acid (in the Bliss serum, right) and mulberry (found in Olay's overnight mask, here) are called tyrosinase inhibitors. They work by blocking the enzyme responsible for stimulating melanin so that hyperpigmentation will never get a chance to show up on your skin, says Dr. Zeichner.

9. The 3 p.m. soda addiction.

What's the big deal? Your guilty pleasure isn't just full of wrinkle-inducing sugar (yes, sweet stuff contributes to aging), it's also highly acidic, says Dr. Graf. Healthy skin cells are formed when our internal systems are balanced at an alkaline (read: nonacidic) pH. When the environment is too acidic, cells produce less healthy offspring, causing everything from flakes to pigmentation problems to deep wrinkles.

The fix: Switch to a clear bev (dark soda contains more acid-producing phosphorous), says Dr. Graf. Or spike the dark stuff with alkaline-producing lemon. Moisture-attracting humectants, like glycerin or hyaluronic acid (in Garnier's and Philosophy's, respectively), help strengthen weak skin cells.