Sleep disorders in children are a major concern for parents and one of the most common problems seen in clinical pediatrics. Poor sleep has many consequences and can affect all aspects of child development. In addition to the maturation of the nervous system, parental behaviours regarding sleep, the physical sleep environment, characteristics proper to the infant, standard of living and other family characteristics can all influence sleep habits.
This paper presents a portrait of the sleep-wake rhythm of Québec infants approximately 5 months of age, and indicates the factors that may impede the consolidation of nocturnal sleep. Future years of the Longitudinal Study of Child Development in Québec (ELDEQ 1998-2002) will help verify whether sleep problems identified at 5 months will have persisted. Associations between poor sleep and the physical, cognitive and social development of the child can therefore also be studied.