If you’ve ever planned an at-home spa day, there’s a good chance your regimen included a sheet mask. Sheet masks are everywhere: You can pick one up for a few bucks at the drugstore or splurge on a high-end mask from your favorite beauty retailer. But should you use them? And do they even work? We asked dermatologists to weigh in on sheet masks. Who should (and shouldn’t) use them? What ingredients should you look for? Which masks are right for different skin types? And of course: Do sheet masks really do anything? Here’s what the experts had to say.