Insomnia is a symptom characterized as inconsistent or ineffective sleep patterns that can significantly impact a person’s quality of life. There remains a lack of knowledge specifically related to assessing and managing insomnia in cancer patients. Many pharmacological and nonpharmacological therapies are available that can be helpful. All nurses in all settings can play an important role in advancing the knowledge and skills related to addressing insomnia. Though it is a common symptom noted by cancer patients, especially those undergoing aggressive forms of treatment, research regarding insomnia in cancer patients is scarce. This chapter will apply as a model for assessment and treatment of insomnia to cancer patients; however, these principles can also be considered for patients without cancer.