This review attests to the fact that the connections between sleep and developmental issues including cognitive, developmental and emotional domains in early-to-late childhood are more complex than as reflected in early writings. In the face of broad and multifaceted nature of the fact, this work is relatively concise in coverage. Research has indicated significant changes from birth to early-childhood in sleep characteristics in terms of sleep patterns and sleep duration. Children show significant variation in their sleep characteristics as a function of environmental conditions and internal factors such emotional states or physical conditions. The qualitative and quantitative changes in sleep patterns during the early-childhood appear to be occurring in consonant with developmental features and implicated in cognitive, behavioral and emotional development of child. Even though the number of studies in children and adolescents is scarce, the associations between trouble sleep and emotional dysregulation have consistently reported that persist from childhood into early- to mid-adolescence. This review addresses three topics with regards to the importance of sleep in the childhood: i) characteristics of sleep and alteration in these characteristics from infancy to early childhood including development of more complex structures resemble adult sleep and consolidation of sleep wake cycle accompanied by quantitative changes in daytime naps and nighttime sleep; ii) associations between sleep and developmental domains, particularly cognitive and emotional development; and iii) importance of healthy sleep habits and sleep hygiene. The empirical evidence and theoretical considerations within the literature are refined and discussed herein.