Syncope happens when the brain doesn't receive enough oxygen, blood or sugar. SingHealth Polyclinics explains how syncope occurs and what to do when you feel faint.
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What should I do if I suddenly feel faint?Try to call for help immediately. If there’s no one around, call 995 for an ambulance.As the most common cause of fainting is vasovagal, the best thing to do is to sit, squat or lie down.If you have diabetes and are on oral diabetic medication, and have missed or delayed a meal, quickly suck on a sweet as you may have low blood sugar.See a doctor as soon as possible.
How does fainting (syncope) come about?
Fainting generally refers to a momentary loss of consciousness. This generally occurs when the brain doesn’t receive enough oxygen, blood or sugar. In the case of fits, fainting is due to a surge of electrical impulses originating from the brain.
The typical fainting spell is the result of the body overreacting to certain triggers, such as the sight of blood or extreme emotional distress. This is called a “vasovagal syncope”.
During such an episode, the vagal nerve (from the brain) causes the heart rate and blood pressure to drop, reducing blood flow to the brain. Since blood carries oxygen to the brain, this deprives the brain of oxygen, leading to a “black-out”.
When someone faints, the body typically goes from a standing to a lying position. This helps the blood to flow to the brain since the blood doesn’t need to be pumped against gravity. The person will often regain consciousness spontaneously after a few minutes.
How serious is fainting?
Most cases of fainting are benign, but this should never be assumed. Syncope could mean a serious – even potentially fatal – condition such as irregular heartbeats, epilepsy, very low blood sugar (hypoglycaemia), sudden blood loss or cardiac arrest. If you lose consciousness, you should be properly assessed by a medical practitioner.
For more information on
how to help someone with syncope, see previous page.