Across decades and disciplines, a quiet habit formed in childhood — the regular reading of books — has emerged as one of the more consequential investments a young mind can make. Research now demonstrates that children who read regularly grow into adults with measurably lower stress, stronger cognitive function, and fewer mental health struggles, with effects persisting long after the books are set down. The finding reframes literacy not merely as an academic skill but as a form of preventive medicine, one whose benefits accumulate slowly and pay out across a lifetime.