Fainting (syncope) is a sudden and brief loss of consciousness. In some cases, the person both faints and falls to the ground ("passes out"). There are several potential causes of fainting, but the most common is a brief drop in the blood supply to the brain. People with mental disorders such as specific phobias, eating disorders, panic disorder and others may sometimes experience fainting as a symptom. In addition, patients who use certain medications (including antipsychotics and antidepressants) to treat emotional disorders may experience fainting as a side effect.

Just before a person faints, the skin may appear pale and their muscle tone may relax. The person may feel weak or nauseated, and have a sensation that surrounding noises are fading into the background. After fainting, a person usually regains consciousness within a couple of minutes and quickly makes a complete recovery.  

In many cases, fainting is a medically harmless condition that should not worry the patient. However, in other cases fainting may be caused by a serious underlying medical condition. For this reason, all episodes of fainting should be viewed as potentially serious until a physician has had a chance to examine the patient and diagnose the cause of these episodes.

A physician may use several tests to help determine the cause of a patient’s fainting. During a tilt-table test, the patient lies flat on a table which is slowly tilted (head side up, feet side down) while blood pressure and heart rate are monitored. This can provide important information about how the gravitational stress (the force of gravity which causes the blood volume to move towards the feet when tilted) on the body’s autonomic nervous system (ANS) may trigger fainting. Tests that record the function of the heart and brain can also provide insight into the causes of fainting. However, in some cases the cause of fainting cannot be identified.