A new study on preschoolers attending full-day child care in licensed day care homes has found increases in cortisol, a stress hormone, when the children are in child care that exceeds their levels at home. The increases were larger in day care homes where providers were intrusive or overcontrolling. This study followed 150 mostly White, largely middle-class 3- and 4-year-olds in 110 different family child care homes.