Vasovagal syncope is fainting caused by a complex nerve and blood vessel reaction in the body. It’s the result of an abnormal reflex in the body and is often called reflex syncope. It’s the most common cause of fainting. Unlike other causes of fainting, it’s usually not a sign of a problem with the heart or brain. Many triggers can cause vasovagal Syncope, such as: Standing for long periods. Too much heat. Intense emotion, such as fear. Intense pain. The sight of blood or a needle. Exercising fo