One night your baby sleeps through. The next, they're up every hour. Sleep regressions can feel like a mystery—or a crisis—but they are actually a sign of healthy development. This warm, evidence-informed guide explains why sleep regressions happen at key ages, how to distinguish them from other sleep problems, and what you can do to support your baby and yourself through each phase. From the classic four-month transition to the bumps at eight, twelve, eighteen, and twenty-four months, you will learn gentle strategies for responding to night wakings, protecting naps, and preserving your own well-being. With practical routines, checklists, and scripts for common scenarios, this book helps you navigate the hardest nights with patience and perspective. Sleep regressions are not a setback—they are a stage. And they will pass. Part of The New Parent Library.