Infant sleep development : location, feeding and expectations in the postnatal period.

Coping with sleep disruption is a common difficulty faced by new parents. Here we take a critical, contextual and evolutionary perspective on recent evidence surrounding the development of normal infant sleep in the postnatal period, its relationship with feeding method and the relevance of sleep location. Firstly, we explore the question of defining ‘normal’ infant sleep, considering the timing of sleep consolidation, cross-cultural and historical perspectives, and the impact of feeding method on infant waking and parental tiredness. In the second part of the review we focus on infant sleep location, physiological and behavioural functioning and sleep safety. We summarise recent research exploring the consequences of alternate infant sleep locations, including in-hospital interventions testing the effect of these sleep locations on outcomes associated with mother-infant proximity. Finally we provide an up-to-date review of SIDS research, including case-control and cross-cultural studies that inform policy-creation and authoritative advice to parents. We find that many researchers still neglect crucial variables affecting infant sleep including sleep location and feeding method and conclude that whilst the field of infant sleep research is well-established, future studies would benefit from consideration of infant evolutionary biology and the heterogeneity of infant care practices, which would lead to valuable new research insights in understanding normal infant sleep