Objective: To test the hypothesis that sleep disruptions would be evident in 3-year-old children with a history of prenatal marijuana exposure. Design: A prospective study using stratified random sampling beginning in the fourth month of pregnancy. Marijuana and other substance use were assessed by interviews at multiple time points. Offspring were followed up through age 3 years with multidomain assessments at fixed time points, including electroencephalographic sleep studies in the newborn period and at age 3 years. Setting: Primary care, prenatal clinic at a university hospital. Subjects: The sample included 18 children with prenatal marijuana exposure (mean [m=+-SD]age, 39.0m=+-4.4 months) and 20 control children...