Faint Chances

Most people know one simple fact about fainting: It’s embarrassing.

Medically speaking, however, fainting is a fascinating physiological process. And while the embarrassment can be brushed off, the possible causes of fainting should be explored for clues to more serious, underlying conditions.

Who faints: One in five people will have an episode at some time during their lives.

What causes it: In athletes and exercisers, the most common cause is dehydration. In older people, the odds are greater that fainting is linked to an underlying condition. Pregnant women may be more prone to fainting because of their susceptibility to sudden changes in blood pressure. Getting too hot and not consuming enough calories can also predispose a pregnant woman to fainting. In healthy people under 30, the most common causes are over-responses of the vagus nerve (see graphic) and decrease in volume of body fluids.

Warning signs: Lightheadedness, nausea, blurred vision, rapid breathing, sweaty skin. At this point, try to sit down, bend over or lie down. Remove yourself from whatever might have triggered the sensation, such as a hot room.

Coming to: A person should regain consciousness within two or three minutes. Those attending the person should have him or her lie flat and elevate both legs to help blood return to the heart.

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What Happens When You Swoon

The vagus nerve, which extends from the throat to the abdomen, sends out messages that influence swallowing, breathing, heart rate and digestion. Often, stress due to the sight of blood, trauma, pain or anxiety triggers this nerve to respond. Blood pressure drops, heart rate slows and blood flow to the brain drops off. These events combined cause the person to lose consciousness.

Source: “Color Atlas of Human Anatomy.”