Fainting is usually caused by changes in circulatory and nervous systems that cause a drop in the amount of blood, sugar or oxygen that reaches the brain.

An interrupted blood supply to the brain causes the person to lose consciousness and they fall to the floor. Once they are in this prone position, the brain’s blood supply usually rights itself and the person regains consciousness after a couple of minutes.

Most of the time fainting isn’t an indication of a serious underlying condition, although it can be and so shouldn’t be taken lightly, especially if there is no apparent reason for the loss of consciousness.

What Causes Fainting

Fainting can have various causes and these include:

• Hyperventilation: Hyperventilation (breathing rapidly) causes a reduction of carbon dioxide in the blood. Hyperventilation may happen if a person is extremely stressed, has anxiety disorders or is in shock.
• Low blood sugar. Low blood sugar levels can be caused by several different things such as going without food for a long time (or crash dieting). Also at risk are people with diabetes who take insulin shots or other medication. If they don’t eat enough or they take too much medication, their blood sugar levels can drop low enough to make them faint.
• Being pregnant. During pregnancy, the body needs more fluid so it’s easy for pregnant women to become dehydrated. There are also changes to the body, including hormonal changes and changes in the circulatory system. Also, as the uterus grows it can partially block larger blood vessels and decrease the amount of blood that gets to the brain.
• Having anemia. Being anemic means you have fewer red blood cells than normal, and this will decrease the amount of oxygen in the blood supply that is delivered to the brain. A common cause of anemia is iron deficiency.
• Other physical triggers. Being in poorly ventilated rooms, exercising in hot weather, allowing yourself to become dehydrated or too hungry are common physical triggers that can cause fainting. Also, standing up too quickly after sitting for a long period or just standing for a long time can make you faint.
• Emotional stress. Sudden fright, shock, anxiety, or pain all affect the body’s nervous system and can cause a drop in blood pressure, which results in fainting.

How to Tell If Someone May Faint

Sometimes, people may faint without warning. However, there are some signs to look out for which can indicate that a person is experiencing symptoms which might result in them fainting. These include:

•  The patient says they feel nauseous
• Yawning frequently
• Feelings of restless
• Complaints of feeling lightheaded or dizzy
• The skin looks pale, feels cool and may be clammy or sweaty
• Complaining of tightness in the chest
• Having palpitations

What to Do When Someone Faints.

If you or someone you are with feels faint, you should squat, sit, or lie down immediately. If sitting, place the head between the knees. All these positions help the blood flow easily to the brain since the heart is no longer working against gravity.

•  If you see someone faint, lie the person on his or her back and make sure they are breathing. If possible, lift the person’s legs above heart level to aid blood flow to the brain.
•  Loosen all constrictive clothing such as collars or belts.
•  If the person is not breathing, start CPR. Get someone to call 911.
•  Continue with CPR until help arrives.
•  When the person regains consciousness, allow them to rest rather than sitting or getting up immediately.
•  If they are diabetic and have missed a meal, giving them a hard candy or sweet to suck on will help raise their blood sugar levels.
•  Make sure the person who has fainted isn’t jerking or having unusual muscle spasms as this can indicate fitting.

What Not to Do When Someone Faints

Watching someone faint on the television or in a movie is often accompanied by a comedy event, and the other people in the scene respond in equally funny ways. However, these are purely fictional responses and should never be used in real-life situations. You should never, for instance:

•  Slap someone who has fainted
•  Shake someone who was fainted
•  Throw water on them
•  Shout at them
•  Attempt to move them
•  Place a pillow under their head
•  Make them sit or stand up

Most instances of fainting are spontaneous, one-off events with no serious underlying cause. However, conditions such as epilepsy, hypoglycemia, cardiac arrest, blood loss, or irregular heartbeats, all of which are serious, can cause fainting. If you or someone you know has a fainting episode you can’t explain, seek the advice of a doctor.