Want more? There are also peptides that improve hydration. "Keratin-based peptides can repair the skin and hair by helping with moisture and elasticity levels," explained Dr. Hextall. The upshot? Yes, you should totally use peptides if you have any of the above concerns, and unlike a lot of so-called magic ingredients, there’s a lot of data to back them up. The most famous is probably Matrixyl, which was invented by peptide OG Dr. Karl Lintner. A 2013 study found that it can double the levels of collagen in the skin, which is not to be sniffed at. You can find offerings with Matrixyl at a range of price points: I like Paula’s Choice Peptide Booster but The Ordinary has one too ; there's also No7 Protect & Perfect