Vasovagal syncope is a condition that causes people to faint as a result of overstimulation to the vagus nerves. The vagus nerves are two large nerves that control many of the body's processes that are involuntary (breathing, heartbeat, etc.). When these nerves are triggered, the blood vessels relax and dilate, which lowers your heart rate and your blood pressure. Blood pools in the lower half of the body, unable to properly reach the brain, thus causing one to faint. Vasovagal syncope is the most common cause of fainting. Here are 5 things you should know about it.