Fainting is loss of consciousness caused by a temporary lack of oxygen to the brain. Known by the medical term "syncope," fainting may be preceded by dizziness, nausea, or a feeling of extreme weakness. When a person faints, the loss of consciousness is brief and he/she will wake up as soon as normal blood flow is restored to the brain. Blood flow is usually restored by lying flat for a short time, which puts the head on the same level as the heart so that blood flows more easily to the brain. A fainting episode may be completely harmless, but it can also be a symptom of a serious underlying disorder. Fainting should be treated as a medical emergency until the cause is determined.

Fainting can be caused by extreme pain, fear, or stress, standing still or erect for too long, osteoarthritis of the neck bones, a...