1. Fainting 101
Fainting happens when blood flow to the brain is interrupted and oxygen to the brain decreases. Medically known as syncope, warning signs include sweating, dizziness, nausea or weakness, followed by falling unconscious. The loss of consciousness is temporary, and laying down flat on your back restores blood flow and helps you revive within 30 minutes. Sometimes causes of fainting relate to a medical condition, exertion or anxiety.
2. Blood Pressure Abnormalities Are Linked
Your body's need for oxygen changes, which means the blood vessels and heart rate must react quickly. However, when that reaction time is slow, your blood pressure suddenly drops, causing fainting. This is likely if you're older or if you have diabetes or high blood pressure. Certain medications for high blood pressure or heart problems may cause fainting because they may reduce too much of your blood pressure. Low blood sugar from diabetes or a lack of food may also trigger fainting spells. Low or high blood pressure causes orthostatic syncope, or fainting from sitting or standing too quickly, especially during hot weather. This is derived from orthostatic hypotension, a condition that increases the heart rate and constricts blood vessels. When this happens, blood pools in the leg veins while you're standing, instead of pumping back to the heart.
3. Exercising May Interfere With Heart Functioning
Fainting may result if you have a heart disorder or an abnormal heart rhythm that affects its ability to pump blood. You feel normal while resting, but exercising can be a challenge, particularly if you overexert yourself. Fainting after exercise is called exertional syncope, because the heart rate is raised while exercising, but the disorder causes a sudden heart rate drop after exercising. Low blood flow, combined with dilated veins and arterioles causes the blood pressure to drop and, in turn, triggers fainting.
4. Fear and Anxiety Cause Fainting
Stress and anxiety cause hyperventilation, which lowers carbon dioxide levels throughout the body. This condition, also known as overbreathing, constricts the blood vessels in the brain and causes you to faint. Fear stimulates the vagus nerve, which helps the functioning of the chest, neck and intestines. Vagus nerve stimulation slows down the heart and causes cool, clammy skin and nausea, then fainting. Other factors that stimulate the vagus nerve include pain, vomiting, a large bowel movement and even distress over the sight of blood and guts.
5. Mini-Stroke Interferes With Blood Supply
In rare cases, a transient ischemic attack, or a mini-stroke, causes fainting. Blood vessels become blocked, causing an interruption of blood supply to the brain. See a doctor immediately if numbness, confusion, loss of movement in the extremities, trouble speaking or blurred vision occurs after fainting.
