Syncope is the medical term for a temporary loss of consciousness, commonly known as fainting or passing out. Symptoms of syncope include blacking out, feeling dizzy, feeling weak or unsteady when standing, and unstable vision.
People can typically feel an episode of syncope coming on. They may feel nauseous and light-headed and may experience heart palpitations before fainting. Fainting may be prevented if the person lays down and puts his feet up. Three percent of men and 3.5 percent of women are believed to suffer from syncope at some point in their life. It is more common with increased age, particularly in those who are 75 or older.