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 hours per day and gradually decreasing to 9-13 hours between 6-11 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 months of age and on a subsample of 103 infants at 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 ProfileTM 3 (Alpern 2007). We also examined infants’ language understanding through the Italian version of the MacArthur–Bates Communicative Development Inventory (MCDI): Words and Gestures (Caselli & Casadio, 1995; Fenson et al., 1994). 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.
