The importance of sleep to overall health and well-being is becoming increasingly appreciated; however, clinicians may not have a sound understanding of the fundamentals of sleep. This review of normal pediatric sleep is meant to provide a foundation for the pediatric nurse practitioner to develop and use in clinical practice. Key concepts such as normal sleep physiology including biological rhythms and stages of sleep are discussed. Developmental changes in sleep seen in the transition from infancy to young childhood are highlighted, and strategies for instituting and maintaining normal sleep behaviors are recommended. Part 2 of this series will address common sleep problems experienced by young children.