Insomnia is the most common sleep disorder, affecting nearly one-third of all adults in any given year, and chronically affecting 10-15% of the adult population. Reduced sleep time, independent of insomnia, has been associated with a variety of deleterious long term effects, including an increased risk of incident myocardial infarction and symptomatic diabetes. Chronic partial sleep loss or insomnia may impair glucose metabolism in the short term and are associated with the development of diabetes in the long term. Although the extent of sleep loss is more acute in the laboratory-based 'sleep debt' studies of healthy volunteers, chronic primary insomnia patients exhibit 'hyperarousal' (hypercortisolemia in the afternoon and evening, accelerated metabolism) similar to that seen with acute sleep deprivation. In addition, degradations of sleep quantity and quality in primary insomnia have been attributed to cognitive and somatic hyperarousal in the sleep setting. study examines and quantifies in adult men and women the link between primary insomnia and impaired glucose tolerance. This study examines the extent which adequate treatment of primary insomnia reverses impairments of glucose metabolism. If abnormalities of glucose metabolism are reversible, this study will demonstrate the importance of treatment of chronic primary insomnia.