What do Gigi Hadid, Kendall Jenner, and Selena Gomez all have in common? Lately, they've all been spotted wearing the slip dress trend that's been all over the runway the past few seasons (see here here , and here for just a few examples). Whether on its own, dressed down for day or up for night, or layered over a T-shirt with thigh-high boots à la Kendall Jenner, this silky staple makes for an effortlessly sexy outfit that's so '90s, in all the best ways.The best part, though, is that wearing pajamas in public isn't just limited to slip dresses: Cute and comfortable sets are fair game, too. Having already been worn by the likes of Leandra Medine and Mira Duma, Sleeper is the It Girl brand for sleepwear-meets-streetwear. Based around the concept of "walking sleepwear," according to the brand's site, everything available at the online destination is meant to be worn for both bedtime and going out — though we think the pieces look way too pretty for the former.Though they don't come at a fast-fashion price point, Sleeper's offerings are classic pieces with endless styling potential that can easily be worn for years to come. Click on to see what we're adding to our carts — we won't blame you for following suit.