Syncope or fainting is a sudden temporary loss of consciousness that usually is resulting in a fall. When you faint, then you feel unsteady and weak before passing out for a short period which is usually a few seconds. Fainting can occur when you are standing, sitting or when you get up to quickly.
Warning symptoms: In the most cases people are not experiencing warning symptoms before they lose their consciousness and if they experience them, then this will last only for a few seconds.
- Ringing in your ears
- Blurred vision or spots in front of your eyes
- Fast, deep breathing
- Feeling sick (nausea)
- A sudden and clammy sweat
These symptoms are usually followed by a loss of consciousness and strength. When you collapse to the ground, then your heart and head are on the same level. This means that your heart is not working so hard to push blood up to your brain. In the most cases people return to consciousness after about twenty seconds. If you have some friend or family member that have fainting and you have noticed that he does not have consciousness when there have passed two minutes, then you must seek emergency help.
Causes of fainting: When you have a temporary reduction in blood flow to your brain, then is happening fainting. The blood flow to your brain can be interrupted for many reasons such as
- A trigger: One of the most common causes for fainting is a temporary glitch in your autonomic nervous system . This condition in some cases is known as neutrally mediated syncope. The autonomic nervous system is made up of spinal cord, nerves and brain. This part of your body is regulating automatic bodily functions such as blood pressure and heart rate. When there is some external trigger, then this can cause a temporary stop of the work of the autonomic nervous system which results in fainting and a fall in blood pressure. The trigger can also cause your heartbeat to pause or slow down for a few seconds which is resulting in temporary interruption to the blood supply of your brain. This condition is known as vasovagal syncope. This trigger can be:
- Sitting or standing up suddenly – condition known as PoTS (postural tachycardia syndrome) 
- Laughing 
- Coughing 
- Sudden pain
- An unpleasant sight
- Heart problems: Heart problems can also interrupt the blood supply to your brain and cause you fainting. This type of fainting is known as cardiac syncope.  The risk of getting this condition is increasing with age but also you have increased chances to get this condition if you have:
- Repeated episodes of fainting that come on suddenly without warning
- An abnormal electrocardiogram which is a test that checks for abnormal heart rhythms
- Structural problems with the muscles of the heart
- Weakened heart chambers
- Chest pain
- Narrowed or blocked blood vessels to the heart
- Had a heart attack in the past
- Low blood pressure when you stand up: If you fall in your blood pressure, then this also can lead to fainting. This condition is known as orthostatic hypotension and usually affects older people, especially those who are aged over 65. Diabetes, neurological conditions (such as Parkinson’s disease), medication and dehydration are possible triggers of orthostatic hypotension. 
- Reflex anoxic seizures: This type of fainting is occurring in young children. This condition is caused by involuntary slowing of the heart rate to the extent where our heart stops beating for five to thirty seconds. In this condition child is opening their mouth as they are going to cry but they are not making any sound before they turning pale grey and they lose their consciousness. They will become limp but in the most cases they are becoming stiff. Their eyes are rolling upwards and their fingers are clawing. Also their bodies can jerk a few times. These seizures usually last less than a minute. After this, your child will regain consciousness and may be sleepy and confused for a few hours. This condition is frightening but they are not dangerous and they will not harm your child. 
Above are some of the causes of fainting.
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 American Academy of Neurology. Feel lightheaded when standing up? You may have a greater risk of dementia. Science Daily. 2018. Retrieved from www.sciencedaily.com/releases/2018/07/180726090119.htm
 Haddad C, Haddad-Lacle JEM. Laughter-induced syncope. BMJ Case Reports. 2013;2013:bcr2013010169.
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 Harvard Heart Letter. What’s at the heart of fainting? 2012. Retrieved from https://www.health.harvard.edu/heart-health/whats-at-the-heart-of-fainting
 Horrocks IA, Nechay A, Stephenson JBP, Zuberi SM. Anoxic-epileptic seizures: observational study of epileptic seizures induced by syncopes. Archives of Disease in Childhood 2005;90:1283-7.