Sleep is an important aspect of a child's early development and is essential to family well-being. During their first 3 years, infants and toddlers spend more than 50% of their lives sleeping. However, concerns about sleep and sleep problems are among the most common issues brought to the attention of pediatricians. Although sleep is one of the most natural things a baby can do, it presents enormous challenges for many families, with studies finding that a large number of young children (from 20% to more than 50%) have a sleep problem. The authors review the prevalence and treatment of common sleep issues.