You've said it before: "I need my beauty sleep!" as you crawl under the covers for a well-deserved full night of rest. But while you might be saying it facetiously, there are ways to slow down signs of aging overnight. But first: doesn't sleeping cause wrinkles?

Yes, it can. According to Debra Jaliman, MD, a New York City-based dermatologist and author of Skin Rules ($13; amazon.com), sleeping in such a way that your face comes into contact with cotton pillowcases like on your side or stomach can lead to the creation of deep sleep lines on your forehead and cheeks.

Wrinkles are caused by the loss of collagen and elasticity, which reduces skin volume. But applying repeated pressure (such as sleeping with the side of your face on a pillow) or muscle motions (such as laughing and squinting) against the collagen will promote its breakdown, eventually leading to visible lines.

Here are the eight ways that you can prevent wrinkles while you rest.

Sleep on your back

Sleeping on your stomach or on of your sides means there is constant pressure on your face. Over time, this action will produce unwanted sleep lines. You can remedy this by sleeping on your back, says Dr. Jaliman, this way you will not apply any pressure to your face. For many people though, this might be uncomfortable, and you can't control your involuntary sleep movement leading you to a side or stomach position. But, you can practice and can get used to it over time.

 

Not a back-sleeper? Get a special pillow

Dr. Jaliman recommends the NIGHT Pillow ($150; amazon.com) for sleep. "It has many benefits including minimizing wrinkles, supporting clean skin, and assisting with hydrating your skin cells, which helps prevent the formation of fine lines," she says.

If you do want to promote sleeping on your back, try the Nurse Jamie Beauty Bear Age Delay Pillow ($69; dermstore.com), which is a contoured pillow designed to reduce facial contact with the pillow surface, reducing sleep lines.

There's also a lower-tech option for those who want to become back sleepers. You know those pillows they sell in airports so you can sleep comfortably on long flights? You can use them in bed, too. They make it easier to sleep on your back without eventually rolling onto your side. Try the Nap uPillow ($20; amazon.com), which uses silky-soft fabric for soothing support.

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Upgrade your pillowcase

If you just can't get comfortable sleeping on your back, you can still prevent those pillowcase-induced wrinkles by upgrading from cotton to silk or satin. "With a silk pillowcase, your skin slides on the pillow," says Dr. Jaliman. In other words, there is less traction and your face won't "crunch" against it like it does on a cotton pillow. Try the Spasilk Facial Beauty Pillowcase ($20; amazon…

 

Jennifer Lopez doesn’t need a cape to look and feel like a superhero.

On Wednesday, the “El Anillo” singer, 49, showed off her buff biceps in a clingy maroon dress and silver hoop earrings on Instagram. With her hair swept back, Lopez flexed her incredible arms as she looked confidently at the camera over her shoulder.

“Feeling like superwoman after the show tonight!” Lopez wrote.

In the caption, Lopez reflected on her jam-packed residency at Planet Hollywood in Las Vegas, which comes to a close on Sept. 29.

“When I started this run I thought omg 15 shows in 27 days that’s a lot,” Lopez explained. “But I made a promise to myself that instead of letting it wear me down I would be even stronger at the end of it…I will work out and be in the best shape of my life…”

RELATED: Jennifer Lopez Is Missing Boyfriend Alex Rodriguez After Having Spent Just ‘One Day Apart’

She continued, “There were moments I was tired and there was travel and I had to fit in my workouts where I could… but here we are with only 3 shows left!! And I am having so many emotions but mostly just feeling strong, happy and grateful!!!”

Lopez tacked on the hashtags “#allihavefinal15,” “#3showstogo,” “#we’renotdoneyet,” “#letsgoooo” and “#makepromisestoyourselfandkeepthem.”

One way that Lopez stays refreshed for her performances is her pre-show ritual.

Before Lopez’s show earlier this month, her boyfriend Alex Rodriguez filmed Lopez grooving in front of a mirror while Cardi B‘s verse on their song “Dinero” played in the background.

“She does this before every show. Seriously,” Rodriguez quipped in the caption.

But it’s not all fun and games: Lopez revealed to Entertainment Tonight in August that she once suffered a dental disaster onstage.

“I’ve chipped my tooth on stage and had to finish the show,” Lopez said. “Like, literally knocked my tooth out and I’m like, ‘Oh!’”

RELATED: Jennifer Lopez & Alex Rodriguez Dine at Same L.A. Restaurant as Her Ex Casper Smart

People backstage motivated her to finish strong. “I went back thinking, ‘Can I finish the show like this?’ They’re like, ‘Yeah, yeah, it’s fine, it’s just a little chip,” she recalled.

Let’s be honest, cold weather doesn’t do your skin any favors. All of a sudden, your hands feel like sandpaper and you may find yourself wondering, Since when is eyebrow dandruff even a thing? Believe it or not, dermatologists have the same winter skin problems, and they have to deal with them just like the rest of us.

When the air starts to chill, your body tries to hold in heat by narrowing the blood vessels, says Debra Jaliman, MD, dermatologist and assistant clinical professor of dermatology at Icahn School of Medicine at Mount Sinai Hospital in New York City. As a result, she explains, the outer layers of the skin become dry and dull, leading to pesky problems like flakes and cracks. But the cold doesn’t discriminate, meaning even skincare professionals have to resort to strict winter skincare regimes.

We spoke with six dermatologists and got the inside scoop on how they care for their skin when the weather gets cooler. Sure, what they tell us when we're sitting in the patient chair is one thing, but the advice they actually take themselves, now that’s a whole different story.

RELATED: 7 Genius Ways to Prevent Wrinkles While You Sleep

Cleanse without drying out the skin

"First, I wash my face with a hydrating cleanser," says Joshua Zeichner, MD, director of cosmetic and clinical research in the department of dermatology at Mount Sinai Hospital in New York City. The key word here: hydrating. "Especially in wintertime, it’s important not to strip the skin of essential oils,” Dr. Zeichner adds. Neutrogena Ultra Gentle Hydrating Cleanser ($8; amazon.com) is his go-to during dry, frigid months, since it gets his skin squeaky-clean without compromising its protective barrier.

Deanne Robinson, MD, FAAD, president of Modern Dermatology of Connecticut, says she relies on ISDIN Micellar Solution ($28; amazon.com) for the same reason. She prefers non-soap cleansers like this one to remove makeup while hydrating at the same time.

RELATED: 7 All-Natural Deodorants That Actually Work

Use a sheet mask for moisture

Sheet masks allow rejuvenating ingredients to really soak into the skin, Dr. Jaliman says, which is why she puts one on right when she hops out of the shower. Her all-time favorite is Lierac Paris Comfort Mask ($22; dermstore.com). “This is good one to try because it contains shea butter, mango butter, and apricot oil,” she says, adding that these three ingredients have high concentrations of nourishing vitamins and fatty acids.

Moisturize, moisturize, moisturize

It's no secret your skin needs a moisture boost when humidity drops. Every dermatologist we spoke to stressed the importance of moisturizing as the seasons change, but they all had a slightly different way of doing so.

“I prefer ceramide-based products because this fatty acid is essential to our skin barrier and function,” Dr…