Don't smoke. Don't skip the sunscreen. Don't skimp on beauty sleep. These are the rules we've been taught to follow if we want to hold onto happy, youthful skin—but we could be sabotaging ourselves without even realizing it.

Expensive moisturizers, masks, creams, and serums aren't necessarily a great investment if we drop the ball when it comes to other areas of our lives—and we aren't talking about pulling the occasional all-nighter. Here are a few ways your everyday routine could be making you look older.

1. Sleeping on a Cotton Pillowcase

Do you ever notice how you wake up with creases on your face after a good night's sleep? "Many people sleep on their face, which can cause sleep lines or wrinkles," says dermatologist Marie Jhin, M.D. of Premier Dermatology. "I love silk pillowcases—they can help with this."

And they're not even as crazy-pricey as you might think, given that they're made out of silk. A high-quality, 100-percent pure silk pillowcase from Alaska Bear will set you back $23, which ain't a bad investment. And bonus: It's also better for your hair.

2. Enjoying Happy Hour a Little Too Much

A $6 Moscow Mule is hard to resist, especially after working a grueling eight-to-nine all week. Drinking booze in moderation has its benefits, including an increase in your HDL cholesterol levels (that's the good kind), as well as lowering your risk of Alzheimer's and dementia. But indulging in more than one or two glasses a day can undo all those amazing benefits.

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Pouring it up too much reduces the amount of collagen (a protein that keeps your skin looking supple) and causes redness brought on by dilated blood vessels. "Consuming too much alcohol is definitely something that can have an effect on the skin because of how dehydrating it is," says Maggie Michalczyk, RDN, founder of Once Upon a Pumpkin. "The alcohol is pulling moisture out of the skin, and this dehydration works to speed up the process of wrinkle definition and inflammation to the skin."

3. Multitasking

Doing the absolute most 24/7 might impress your boss, but it's likely wreaking havoc on your health. When you multitask, your body experiences higher amounts of stress than when you apply your focus to one task at a time.

"Chronic stress may affect the skin in adverse ways, especially in aging," says William Kwan, M.D., a board-certified dermatologist and ethnic skin care expert in San Francisco. "Stress can lead to an increase in inflammation in the skin. This inflammation releases mediators, which can destroy collagen and connective tissue, possibly affecting epidermal maturation."

4. Overusing Your Central Air and Heating System

Freezing one minute, hot like a sauna the next? Back-and-forth temperatures are annoying AF, but overusing your central air and heating system dries out your skin because all the moisture is sucked out of the air in your home or apartment, making fine lines and wrinkles even more noticeable. "Dry skin leads to inflammation," says Dina D. Strachan, M.D., a board-certified dermatologist and director of Aglow Dermatology in New York City. "We lose collagen and elastin in our skin with age. Inflammation accelerates this process."

If you absolutely need to crank up the AC or heating system, give your skin a dose of TLC with a super-hydrating night cream, like the Lavender Age Corrective Night Concentrate from Eminence Organics. Drink plenty of H2O and consider getting a humidifier and placing it in your bedroom, living room, and wherever else you spend the most time as well.

5. Cutting Out Fats From Your Diet

Not all fats are created equal. Unlike trans fats, for instance, monounsaturated and polyunsaturated fats are "healthy" fats—and they're great for your skin, says Deepa Verma, M.D.

"Fats have been demonized," Verma says. "But we actually need them—they're building blocks for hormones and are responsible for cell membrane integrity, and getting enough good fats can result in healthy, glowing skin."

So what are some sources of the right kind of healthy fats that will make our skin glow? "Avocados are associated with anti-aging due to the compound xanthophyll, and they also have vitamin E, which provides skin with increased collagen synthesis and elasticity," Verma says. "Sunflower seeds are another good one—they have vitamin E, and are a rich source of selenium and copper, which help maintain youthful and radiant skin. They're also packed with omega-6 and linoleic acid, which help with skin cell regeneration."

And don't forget to get your omega-3s too. "Omega-3 can be derived from fish, but there are plant sources as well, such as chia, flax, and ahiflower," Verma says. Certain omega-3s can block the release of UV-induced enzymes that degrade collagen, which cause lines and sagging skin—basically, sources of omega-3 can help prevent and repair sun damage.

6. Spraying Perfume on Your Neck

We grew up watching our mothers and grandmothers spritz perfume on their "pulse" points—neck, wrists, and décolletage. They're full of wisdom about life's lessons, but the skin on your neck is delicate, so applying perfume to that area is a no-no.

The alcohol in fragrances is super drying—and can be especially problematic if you spray it on right before stepping out into the sunlight, which puts you at a higher risk of developing a skin condition called Poikiloderma of Civatte, which is basically skin discoloration due to prolonged periods of sun exposure.

"Perfume can contribute to this skin condition, as some of the ingredients react to UV exposure, creating a toxic molecule to the skin," explains Ava Shamban, M.D., a dermatologist in Santa Monica and founder of SKINxFIVE. Instead, try spritzing a brush and running it over your forearm, clothes (avoid silk and other delicate fabrics), and hair. Shamban also suggests using sunscreen and clothing (i.e., lightweight scarves) to shield the sensitive skin on your neck and décolletage against damaging UVA and UVB rays.

7. Sipping Your Drink Through a Straw

Straws fight off teeth stains and minimize cavities, but the downside? The "repetitive motion" of pursing your lips can cause wrinkles to form around the mouth, Shamban says. Our solution? Skip the straw and try one of these teeth-whitening tricks instead.

Princess Gabbara is a multimedia journalist and storyteller. Follow her on Twitter and Instagram @PrincessGabbara.

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