Relationship between sleep/wake patterns, temperament and overall development in term infants over the first year of life.

Background: This study sought to assess the relationship between the development of infant sleep/wake patterns, temperament and overall mental, motor and behavioural development over the first year of life. We hypothesised that infants with more regular sleep/wake patterns and longer sleep durations would have an easier temperament and higher developmental scores.

Study Design: Sleep/wake characteristics were recorded with the use of both parental sleep diary and actigraphy (Actiwatch AW64, Mini Mitter Company Inc, Sunriver, OR, USA) in 20 healthy term infants at monthly intervals over the first year of life. Temperament was assessed using the Early Infant Temperament Questionnaire (EITQ) at 3 months and the Revised Infant Temperament Questionnaire (RITQ) at 6 and 11 months and mental, motor and behavioural development at 12 months using the Bayley Scales of Infant Development II (BSID-II).

Results: At all 3 ages studied increased nocturnal sleep was correlated with increased approachability. In addition, at 11 months increased diurnal sleep duration was also correlated with increased rhythmicity and adaptability. At 12 months of age decreased daytime sleep duration was correlated with emotional regulation.

Conclusions: Our findings highlight the importance of considering maturational and regulatory aspects of sleep when evaluating infant daytime behaviour. We suggest that concerns regarding sleep characteristics should become a significant aspect of clinical assessment and diagnosis of developmental delay or behaviour problems, particularly in the first year of life.