PURPOSE/OBJECTIVES: To update the state of the science on sleep-wake disturbances in adult patients with cancer, focusing on insomnia in the areas of prevalence, mechanisms and models, measurement, interventions, and implications for practice, health policy, education, and research. DATA SOURCES: Published articles, books, book chapters, MEDLINE, CINAHL, and PsycINFO computerized databases. DATA SYNTHESIS: Since the 2004 conference on Sleep-Wake Disturbances in People With Cancer and Their Caregivers, an increased focus has existed on the prevalence and distress experienced by patients with cancer with sleep-wake disturbances, particularly insomnia. Evidence suggests that altered physiology directly related to the cancer process may play a prominent role in disrupting sleep, circadian rhythms, and hypothalamic-pituitary-adrenal axis-regulated processes. Reliable and valid objective and subjective measurements for screening and assessing sleep-wake disturbances are ready for use in clinical and research settings, and an increasing amount of intervention studies have reported sleep-wake outcomes in adult patients with cancer. CONCLUSIONS: Cognitive behavioral therapy interventions are likely to be effective, but effectiveness has not been established for complementary, education or information, or exercise interventions. IMPLICATIONS FOR NURSING: Multidisciplinary research teams should test the effectiveness of interventions to reduce sleep-wake disturbances in adult patients with cancer. Settings should create the infrastructure to initiate and sustain evidence-based oncology nursing practice, clinicians should educate the public about sleep, and public policies should promote adoption of healthy sleep patterns and early diagnosis and treatment of sleep disorders. Abstract for this article also available on page 401 of printed version. The full text of this article can be accessed at www.ons.org/publications/journals/ONF