The purpose of this study was to describe the daytime activity levels and their association with sleep, fatigue, depressive symptoms, and quality of life. Wrist actigraphy and questionnaires were used to examine 51 mothers with a preterm infant during their second week postpartum. Circadian activity rhythms (CAR) were less synchronized in these mothers; they experienced sleep disturbances, fatigue, depressive symptoms, and poor health-related quality of life (H-QOL). Compared to high-activity mothers, mothers with low activity levels slept less during nighttime but napped more during daytime, and reported more postpartum depressive symptoms. Further research is needed to examine the effect of low activity level and sleep loss on postpartum depression, and to develop interventions for improving rest/activity patterns for new mothers.