Establishment and consolidation of the sleep-wake cycle as a function of attachment pattern.

The development of sleep-wake regulation in infants depends upon brain maturation as well as various environmental factors. The aim of the present study was to evaluate sleep duration and quality as a function of child attachment to the mother. One hundred and thirty-four mother-child dyads enrolled in the Maternal Adversity, Vulnerability and Neurodevelopment (MAVAN) project were included in this study. Attachment was assessed with the Strange Situation procedure at 36 months and maternal sleep reports were collected at 6, 12, 24 and 36 months. Differences in sleep characteristics were assessed with mixed models with one factor (attachment group) and one repeated measure (age). Children classified as disorganized had a significantly lower duration of nocturnal sleep, went to bed later, signaled more awakenings, had shorter periods of uninterrupted sleep (only at 12 months) and had shorter periods of time in bed (only at 6 months) than children classified as secure and/or ambivalent (p < 0.05). This is the first study to show that children with insecure disorganized attachment present a distinct sleep pattern in comparison with those with secure or ambivalent attachment between 6 and 36 months of age. Sleep disturbances could exacerbate difficulties in these families that are already considered vulnerable.