What happens when you faint?

Fainting is not just one thing
As the term is commonly used, fainting is a sudden and temporary loss of consciousness. The medical term is “syncope,” which comes from the Greek “synkope,” meaning “contraction” or “cutting off.” It’s an apt expression, because syncope occurs due to a sudden reduction in blood flow to the brain. Syncope is remarkably common: about one-third of people report having at least one episode of fainting during their lifetime. But while “fainting” is commonly used to describe otherwise healthy people passing out, it can be due to a number of conditions, ranging from the harmless to the life-threatening.

Some of the most common causes of fainting include:
Vasovagal syncope. 
The name of the condition refers to increased activity of the vagal nerve which signals the heart to slow down and for blood vessels (“vaso-“) to open up. This combination of effects leads to a drop in blood pressure and too little blood flow to the brain. The sight of blood or emotional or physical stress are common triggers for this condition. Straining during a bowel movement or even vigorous coughing may also provoke vasovagal syncope. And so can a warm environment or a feeling of panic or claustrophobia.
Abnormal heart rhythm.
If the heart rate is markedly slow or fast, blood pressure may fall and fainting may follow. Among the many triggers for an abnormal heart rhythm are diseases of the heart itself, certain medications, or an overactive thyroid gland.


Orthostatic hypotension.
This term means a drop in blood pressure that develops when going from lying down or sitting to standing up. Dehydration, medications or drugs (including alcohol), and heavy blood loss are common underlying culprits. The condition also becomes more common with age.

There are many other causes of fainting, such as low blood sugar or seizures. But in many cases, no cause can be found.

Although about 75% of people who faint have nothing serious as the cause, it’s important to get checked out to make sure you’re in that 75%. And even when nothing serious is found, many people injure themselves if they fall when they lose consciousness. People who’ve fainted and who have occupations that involve transporting passengers or the operation of heavy machinery may be advised to restrict activities that could put themselves or others at risk if they faint again.




Pregnancy
Pregnancy is another situation that may make fainting more likely. The blood vessels tend to dilate during pregnancy and blood pressure is normally on the low side. It doesn’t take much to lower the blood pressure enough to cause fainting.

When fainting is fashionable?In some circumstances, fainting at a specific cue — “swooning” or “falling out” — became a cultural expectation. For example, it was common for aristocratic women in Victorian England to faint during a particularly dramatic moment. Examples abound of “hysterical fainting,” where large numbers of people near one another begin to faint due to an assumption of shared disease or exposure to a toxin, or even a curse. And then there’s the game we used to play in the neighborhood to intentionally faint: we’d breathe deeply and quickly for a while and then hold our breath and bear down. It never worked for me — that’s fortunate, since it can be dangerous.

Creadit:  Harvard Health

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