Sleep is essential for good health. Sleep problems are one of the most common issues for which parents seek advice from their pediatricians. These sleep problems are developmentally linked, ranging from difficulty putting infants and toddlers to bed, to night terrors and other parasomnias in preschool- and young school-aged children, to inadequate sleep among adolescents. Sleep problems can affect all children, although certain groups of children are especially at risk. These include infants at risk of sudden infant death syndrome, children with obesity or certain inherited disorders who are at risk for sleep-disordered breathing, children receiving medications (whether they be stimulants or other drugs), children with neurologic disorders or developmental delay, and children with chronic illness both in and out of the hospital. The consequences of sleep disorders can be broad and substantial and include academic, emotional, physical and psychological effects, as well as effects on the parents and family.