A review of frontiers in clinical sleep medicine.

The field of sleep medicine has grown exponentially worldwide. Sleep apnea is linked to the obesity epidemic, which, in some regions of the United States, affects more than one-third of the population. Sleep alterations increase the risk of cardiovascular and cerebrovascular pathology through a diversity of direct and indirect mechanisms. Recent investigations have found a clinical correlation between sleep disorders and diabetes. Obese pregnant women are at high risk for development of sleep apnea and preeclampsia. New studies have uncovered that restless legs syndrome and periodic limb movements may increase the risk of hypertension and vascular disease. Sudden death in sleep may be preventable if conditions that lead to sudden death are investigated. New neuroimaging techniques during sleep in patients with insomnia have uncovered metabolic overactivity in areas of the brain related to maintenance of wakefulness. Sleep neuroimaging promises to have research and clinical diagnostic applications.