The sleep-cycle development of infants is influenced by familial and sociocultural conditions, but there is a lack of knowledge on how parental regulation of infant sleep is related to the specific life situation of a family. This article describes a context-sensitive study of parental regulation of infant sleep that includes the whole 24-hr day, parents' intentions, and familial and sociocultural conditions. The results are based on a longitudinal qualitative study in Norway of 51 families. Parents were interviewed in the infants' first year of life and approximately 18 months later. An interpretive analysis in four steps was conducted, informed by cultural psychological perspectives on development. The parents were found to perform five types of regulatory actions: facilitating sleep, letting sleep, letting be awake, keeping awake, and waking. These actions were performed continuously throughout the 24-hr day, each to different extents and at different hours in individual families, forming a regulation cycle. We describe patterns and variations in regulation cycles, changes over time as increased social synchronization, and how the regulation cycle is embedded in familial and sociocultural conditions. Finally, implications for clinical practice are discussed.