Masks provide a fast, temporary benefit, so they’re great pinch hitters to bring in when your skin is dealing with a situation that needs a quick fix — like when you’re traveling on an arid, moisture-sucking airplane and need hydration, stat.“Sheet masks can provide an instant gratification, because they are often made with high concentrations of moisturizing ingredients,” says Dr. Chiu, who recommends looking for hydrating masks with hyaluronic acid. (We like Karuna Hydrating+ Face Mask .) And as anyone who has ever slapped on a mask an hour before a party can attest, the right ones can brighten, too. Your makeup will look that much better, because “masks can give you a temporary, glowy look,” adds Dr. Chiu. “Vitamin C can brighten skin and pearl powder or extracts can give you amazing, albeit temporary, radiance.” Try Dr. Jart+ Brightening Infusion Hydrogel Mask , which contains both ingredients.Finally, sheet masks can also soothe redness. If you have a blotchy, itchy face, Dr. Chiu recommends masks with aloe vera or green tea to help reduce inflammation. We like Yes to Cucumbers Calming Sheet Mask , which comes loaded with both. Pro tip: “If you keep sheet masks cool in the refrigerator, they can be refreshing and help decrease puffiness and swelling, too,” Chiu says.Yep, turns out, they're not just gimmicky props made for Snapchat: There's a real purpose behind paper or cloth delivery systems. “Sheet masks build on the idea of occlusion,” says Dr. Chiu. “This means you get better penetration as ingredients are essentially ‘pushed’ into the skin by having a sheet on top of them.”What’s more, the sheet actually serves as a barrier, stopping some of the hydrating ingredients from evaporating, Dr. Chiu notes. But that doesn’t mean you can’t make room in your medicine cabinet for jar masks, too. “Sheet masks and traditional masks are used for different reasons and complement — rather than replace — each other,” says Dr. Chiu.For starters, sheets are not ideal if you have breakouts. “For oily or acne-prone skin, I would recommend a non-sheet mask,” says Dr. Chiu. “Clay- or charcoal-based masks draw out excess oils and reduce inflammation. But sheet masks can, at times, create excess warmth that can induce more inflammation and breakouts.” We like L’Oreal Detox & Brighten Pure-Clay Mask , which comes in a jar.Sheets are also not-so-great if you’re looking to get in a major exfoliation session. “Sheet masks generally don’t exfoliate or deep clean your face,” says Dr. Chiu. “Jar masks can have stronger exfoliants.” Try Ole Henriksen Power Bright , a three-step treatment which includes a big dose of brightening vitamin C and exfoliating sugar and pomegranate.We know, we know: Sheet masks are loaded with active ingredients, so they sound a lot like serums, right? Not so fast. “While sheet masks boast a high concentration of active ingredients, like a facial serum, they would be a cost-prohibitive way to address your skin needs daily,” says the derm.