Despite the joy surrounding the birth of a child, numerous studies have documented a robust decline in marital satisfaction across the transition to parenthood. Various hypotheses, each supported by empirical evidence, have sought to explain this decline. This review considers the additional role of sleep loss in the postpartum decline in marital satisfaction. The authors begin by highlighting the problem of parental sleep disruption in a child's 1st year of life and then outline findings related to the affective and cognitive consequences of sleep deprivation and chronic sleep restriction. The demands brought on by the transition to parenthood are reviewed, and the ways in which the consequences of sleep disruption further exacerbate these stresses are considered. The authors suggest that clinicians working with couples who have recently had a child evaluate the extent of sleep disturbance in the family and educate couples regarding the mood and cognitive changes that co-occur with sleep loss. The authors further suggest that future research into the transition to parenthood assess level of sleep loss and that research into the consequences of sleep loss aim to identify individuals particularly vulnerable to mood and cognition changes.