Sleep is such an essential part of human existence that we spend about a third of our lives doing it -- some more successfully than others. Sleep disorders afflict some 50-70 million people in the United States and are a major cause of disease and injury. People who suffer from disturbed sleep have an increased risk of heart attack, stroke, hypertension, obesity, depression, and accidents. Nearly a fifth of all serious car crashes, in fact, are linked to sleeplessness.
Diagnosing sleep disorders is not necessarily easy. In standard "sleep studies," people spend one or more nights at hospitals or other inpatient centers, sleeping while sensors and electrodes attached to the head and torso record breathing, brain waves, heart rate, and other vital signs.