OBJECTIVES: The origins and persistence of psychological morbidity in caregivers are not fully understood. The present analysis examined the relationship between the strain and burden of caregiving and depression and anxiety in a large community sample. Social support and sleep quality were investigated as potential mediators. DESIGN: Cross-sectional and prospective observational study. METHOD: Individuals caring for someone other than their own child (N=393) were identified from a population of 2,079. Caregiving strain and burden, social support, and sleep quality were assessed. Participants completed the hospital anxiety and depression scale at the same time and 5 years later. RESULTS: Caregiving strain and burden were associated with depression and anxiety symptoms cross-sectionally, and with a worsening of symptoms 5 years later. Sleep quality appeared to mediate the cross-sectional relationships. CONCLUSIONS: The demands of caregiving and associated sleep disruption contribute to symptoms of depression and anxiety in caregivers.