What is fainting?
Fainting is a temporary loss of consciousness and muscle tone. It is caused by not having enough blood flow to the brain. Known by the medical term "syncope," fainting may be preceded by dizziness, nausea, or a feeling of extreme weakness.
When there is not enough blood flow to the brain, passing out protects the brain from damage. People who faint generally lose muscle tone and fall to the ground. When someone is lying on the ground, the blood being pumped out of the heart doesn't have to fight gravity to get to the brain. Those who faint have a relaxed body, which uses less energy. This also makes it easier for the heart to pump blood to the brain. When a person faints, the loss of consciousness is brief. The person 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. This position 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 and of no significance, but it can be a symptom of a serious underlying disorder. No matter how trivial it seems, a fainting episode should be treated as a medical emergency until the cause is determined.