In this review, we describe postpartum sleep as characterized by marked fragmentation, resulting in nearuniversal fatigue during the initial postpartum period. This sleep disturbance and fatigue are major contributing factors to the onset of affect and mood disturbance, which in turn is strongly associated with an increase in negative infant-parent interactions and adverse infant emotional and cognitive outcomes. Although less-frequently studied, postpartum fathers also experience sleep disturbance and sleepiness associated impairments that impact their families. Despite this, postpartum sleep should be considered a normative developmental period, and the need for intervention can be seen as a byproduct of social and economic expectations that new parents return to the workforce soon after childbirth. Heretofore, there is little evidence to support the efficacy of interventions to improve parent sleep, though some suggest that socially disadvantaged families may benefit most from advice regarding infant and maternal sleep. Also reviewed here is the evidence for a high proportion of children reported to co-sleep with their parents – despite the professional recommendations in the United States – and the need for family education regarding safe co-sleeping. Finally, one obstacle to a woman’s decision to breastfeed may be concern about how this will affect her sleep; the evidence for a lack of impact of infant breast feeding on maternal sleep is evident.