This study explored the links between mothers' objective and subjective sleep and their caregiving feelings toward their infant (i.e. patience for the infant, desire to be with the infant, and anger toward the infant), using a diary study design. We were particularly interested in examining whether nights of lower sleep quality within individual mothers predict more negative maternal caregiving feelings the following day. The sample included 151 women, who were recruited during pregnancy. Data were collected at 4 and 8 months after delivery. Maternal sleep was monitored at home for seven nights using actigraphy and sleep diaries. Mothers rated their caregiving feelings each evening. Multilevel modeling (controlling for depressive symptoms, feeding method, and background variables) revealed that actigraphic and subjective sleep variables were associated with maternal caregiving feeling, both at the between- and within-person levels. For example, lower sleep percent predicted reduced levels of maternal patience for the infant at 4 and 8 months (between-person effect). Moreover, when a mother had a lower sleep percent on a given night (compared to her average), she reported lower levels of patience for her infant the following day (within-person prospective effect). The findings demonstrate, for the first time, that maternal nightly variations in objective and subjective sleep quality predict daily changes in maternal feelings toward her infant at two different assessment points. Improving maternal sleep quality might be an important target for future interventions which may help mothers to feel more positively toward their infants.