Insomnia is the most common sleep disorder reported by cancer patients. Oncologists have noticed that alterations in sleep patterns are endemic among their patients, yet sleep problems are rarely assessed in a typical patient evaluation. Other concerns, such as morbidity and mortality, appear to take precedence. The cause of chronic sleep difficulties is multifaceted and up until recently, little attention has been given to the potential factors associated with the pathogenesis of cancer-related insomnia. The unique contributions of psychologic, medical, treatment side effects, environmental, behavioral, and pharmaceutical pathways on cancer-related insomnia cannot be ignored. This paper explores an overview of the incidence and severity of sleep disturbance in cancer patients, a review of the mechanisms of sleep, and the potential factors associated with the pathogenesis of cancer-related insomnia. Nurses, physicians, and other healthcare providers are in a unique position to greatly improve the quality of sleep in cancer patients. Cancer patients face many challenges; sleep problems do not have to be one of the necessary consequences associated with the cancer experience.