Insomnia is a disorder marked by one or more of the following complaints: difficulty in initiating or maintaining sleep, waking too early in the morning, or sleep that is chronically non-restorative or of poor quality. Insomnia generally does not resolve spontaneously.To be diagnosed with true insomnia, we must have a problem falling asleep, staying asleep or getting enough rest from sleep that interferes with work or other everyday tasks. Insomnia, not a diagnosis. When the older person suffers from insomnia, the etiology can be multifactorial. Insomnia can signal the presence of other sleep disorders (e.g., sleep apnea, periodic limb movement disorder, and circadian rhythm disorders) and is a health risk factor for depression, anxiety, substance abuse, and suicide. When confronted with a patient’s sleep complaints in practice, the physician is challenged to determine whether the sleep disturbance is caused by, or is causing, a medical or psychiatric condition. Thus, understanding the implications and repercussions of insomnia in older adults, as well as treatment issues specific to this population, is important. Because of the high prevalence, complexity, and health implications associated with sleep-related disorders in older individuals, increasing attention is now being focused on this topic. Health care professionals specializing in geriatrics need to learn to differentiate the different causes of sleep disturbances in this population and to initiate appropriate treatment. This article describes those changes as well as the most common diagnoses and treatments of insomnia seen in the elderly patient. Furthermore, assessment and treatment options for older adults who are 65 years and older will be discussed.