Objective-Sleep disturbances are common among women with breast cancer and can have serious consequences. The present study examined depression, pain, life stress, and participation in group therapy in relation to sleep disturbances in a sample of women with metastatic breast cancer.Methods-Ninety-three women with metastatic breast cancer participated in a large intervention trial examining the effect of the group therapy on their symptoms. They completed measures of depression, pain, life stress, and sleep disturbance at baseline, 4, 8 and 12 months. Results-The results showed that higher initial levels of depression at baseline predicted problems associated with getting up in the morning, waking up during the night, and daytime sleepiness. Increases in depression over the course of 12 months were associated with fewer hours of sleep, more problems with waking up during the night and more daytime sleepiness. Higher levels of pain at baseline predicted more problems getting to sleep. Increases in pain predicted more difficulty getting to sleep and more problems waking up during the night. Greater life stress at baseline predicted more problems getting to sleep and more daytime sleepiness.Conclusions-Depression, pain, and life stress scores were each associated with different types of negative change in self-reported sleep disturbances. Depression, especially worsening depression, was associated with the greatest number of types of negative change. The relationships found between sleep disturbance and depression, pain, and life stress suggest specific ways to address the problem of sleep disturbance for women with metastatic breast cancer and show how different types of disturbed sleep may be clinical markers for depression, pain, or life stress in this population.Keywords sleep disturbance; metastatic breast cancer; pain; depression; stressful life events Corresponding Author: Oxana G. Palesh, Ph.D., Department of Radiation Oncology, University of Rochester Medical Center, James P. Wilmot Cancer Center, 601 Elmwood Avenue, Box 704 Rochester, New York 14642. E-mail: Oxana_Palesh@urmc.rochester.edu, phone: (585) 273-3998, fax: (585) 461-5601. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Disturbed sleep is common among breast cancer patients (Davidson, MacLean, Brundage, & Schulze, 2002;Koopman, Nouriani et al., 2002;Savard & Morin, 2001) and has been found to be associated not only with poor quality of life (Carpenter & Andrykowski, 1998;Fortner, Stepanski, Wang, Kasprowicz, & Durrence, 2002), depressive symptoms (Koopman, Nouriani et al., 2002), and fatigue (Lic...