Why is fainting a useful safety mechanism for the body

Syncope or loss of consciousness for a short time occurs when the brain does not get an adequate supply of blood. The sight of blood, getting a fright, distressing news and standing in the hot sun can all make you feel faint.

According to the American Heart Association AHA , one-third of the global population will faint at least once during their lifetime for any number of reasons. Research shows that in a young, healthy adult, even if the systolic BP the top number falls to 70 mm Hg, the brain gets the blood it needs.

The normal top number for BP is in the range of When we faint after getting distressing news or, say, at the sight of blood, usually it is because of vasovagal reflex - in which the vagus nerve goes into overdrive. The vagus nerve is part of a crucial network that connects the brain to the neck, heart, lungs and abdomen. Ordinarily, it helps the body to relax with every breath, to digest food and perform a host of other functions.

The term doctors use for fainting is syncope say "SING-kuh-pee". Fainting one time is usually nothing to worry about. But it is a good idea to see your doctor, because fainting could have a serious cause. Fainting is caused by a drop in blood flow to the brain. After you lose consciousness and fall or lie down, more blood can flow to your brain so you wake up again. Most causes of fainting are usually not signs of a more serious illness.

In these cases, you faint because of:. Fainting caused by the vasovagal reflex is often easy to predict. It happens to some people every time they have to get a shot or they see blood.

Some people know they are going to faint because they have symptoms beforehand, such as feeling weak, nauseated, hot, or dizzy. After they wake up, they may feel confused, dizzy, or ill for a while. Some causes of fainting can be serious. These include:. Fainting may be the sign of a serious problem if:. To find the cause of fainting, a doctor will do a physical examination and ask questions about the fainting episode. You can help your doctor by being prepared to describe what happened before you fainted, how long you were "out," and how you felt when you woke up.

This may result in fainting. This is more common among older males. Apart from distinguishing episodes of fainting by their underlying cause, one of two different types of fainting might occur:. Losing consciousness is the primary symptom of fainting. The following symptoms may occur leading up to a fainting episode:.

If a person with an underlying health condition faints, they will require treatment. This will help prevent future fainting episodes. Often, however, no further treatment is necessary. To help prevent further fainting episodes, people should try to avoid triggers, such as long periods of standing still, dehydration, and spending a lot of time in hot environments.

If the sight or thought of injections or blood make a person feel faint, they should tell their doctor or nurse before undergoing a medical procedure that may involve this. The doctor or nurse can then make sure that the individual is in a safe position, such as lying down, before starting the procedure. People mainly use beta-blockers to treat high blood pressure. However, some adverse effects of beta-blockers include fatigue , cold hands and feet, a slow heartbeat and pulse, nausea, and diarrhea.

People who feel themselves becoming faint should do the following :. If a person notices that somebody is fainting or about to faint, they can intervene in the following ways:. Here, learn more about how to perform CPR. A fainting episode may be the symptom of a more severe underlying condition, such as stroke.

If the person experiences numbness in the face, paralysis, weakness, numbness in one arm, or slurred speech, they need emergency medical help.

The doctor will listen to the heart to check for underlying cardiac conditions. If they suspect a heart problem, the person may need to see a heart specialist, or a cardiologist. A person can press a button on the Holter monitor if they feel as though they are about to faint. Records will display the heart rhythms that were present at that moment. Physiological shock causes a severe drop in blood pressure and rapid shallow heartbeat.

People often lose consciousness from traumatic injuries, and this physiological shock response is believed to be a mechanism to reduce blood loss. It would not take long to pump the body dry of blood through a serious wound if the heart was pounding wildly.

No wonder females can be more prone to fainting. Fainting from an emotional shock is iconic, especially for females. Fear and other stressful emotional states that provoke a similar shock response in the cardiovascular system that occurs after traumatic injury will cause fainting. Some people faint at the sight of blood, for example. This is believed to be in part a genetically predisposed mechanism that may have had survival value for our ancestors.

Those people who had a hair-trigger response to activating this last-ditch safety mechanism to limit blood loss from trauma survived in prehistoric times long before medical first responders existed. If there is not sufficient oxygen in the blood, a person can faint even if blood flow to the brain is adequate.

Free divers who compete in breath-holding contests skirt the deadly threshold of losing consciousness and drowning. This happened recently to competitive free diver Natalia Molchanova. Impaired lung function or insufficient oxygen in the atmosphere will cause a loss of consciousness. High altitude pilots and mountaineers, for example, are at risk of hypoxia-induced fainting.

However, anything that impairs the delivery of oxygen to red blood cells can result in fainting.