Infant sleep and development: Concurrent and longitudinal relations during the first 8 months of life.

Sleep is an essential function of human life, underlying both biological and cultural processes. Dramatic changes in sleep occur during infancy, in terms of night awakenings, which tend to diminish over time, and day/night sleep duration, with newborns sleeping up to 16-17 h per day and gradually decreasing to 9-13 h between 6 and 11 months of age. Remarkably, research indicates that changes in infant sleep are in interaction with important acquisitions in other domains of child development. In the present study, we aimed at investigating concurrent and longitudinal relations between sleep and cognitive maturation during infancy, by collecting data on 156 infants at 4 and 8 months of age. Infants' sleep was assessed through the Brief Infant Sleep Questionnaire (BISQ; Sadeh, 2004), whereas cognitive maturation was evaluated using the Developmental Profile™ 3 (Alpern 2007). We also examined infants' language understanding through the short form of the Italian version of the MacArthur-Bates Communicative Development Inventory (MCDI-SF): Words and Gestures (Caselli, Bello, Rinaldi, Stefanini, & Pasqualetti, 2015; Fenson et al., 2000). Finally, information about infants' temperament and maternal practices potentially relevant for sleep quality, such as the use of a pacifier at nighttime, co-sleeping and exclusive breastfeeding, was detected. Results showed that night and day sleep were differently related to infants' development at 4 and 8 months of age, but there were no robust longitudinal relationships.