Several recent large clinical trials and meta-analyses have demonstrated that breastfeeding lowers women’s lifetime risk of metabolic syndrome, diabetes and cardiovascular disease in mothers. Further, these studies have documented a dose-response effect: the longer that women breastfeed, the lower the risk. The intriguing question is why this occurs. Research from the field of health psychology provides several possible mechanisms that can explain this effect. In this session, you will learn the many ways that breastfeeding positively affects women’s health. Breastfeeding downregulates the stress response, lowers inflammation, decreases depression, improves mother’s sleep quality, decreases daytime fatigue, and even attenuates the effects of psychological trauma. Results from previous studies will be presented, as well as new data from the Survey of Mothers’ Sleep and Fatigue¸ a survey of 6,410 new mothers.