Sleep dysfunction, in the form of insomnia and/or fatigue, is one of the primary symptoms reported by patients with psychiatric disorders, and specifically those suffering from anxiety and depressive disorders. Conversely primary insomnia and other sleep disorders produce symptoms of mood disturbance that are quite similar to those reported by patients with psychiatric disorders. Because of this overlap in the symptoms and treatments for insomnias and psychiatric disorders, it is important for clinicians to be able to accurately identify the root cause of sleep dysfunction in individual patients in order to optimize treatment. Part of the Oxford Psychiatry Library series, this concise pocketbook provides clinicians with an overview of current understanding of sleep physiology, the pathophysiology of sleep disturbance, and the diagnosis and treatment of sleep disorders.