Losing consciousness is one of the greatest fears that people have about their health. As long as you're alert you can make decisions and contact help if something is wrong. When you're unconscious, you're no longer in control. The prospect of fainting is one of the most frightening things that can happen to someone, with or without anxiety.
So it's no wonder that feeling faint is considered by many to be one of the most frightening symptoms of anxiety. During anxiety - especially intense anxiety - it can feel as though you're about to pass out, and this can spark a fury of panic that is hard to stop.
Only a doctor can diagnose the cause of feeling faint and fainting. There are physical issues that can lead to fainting, such as a heart condition. If you actually faint for no apparent reason, or if you feel like you are going to faint (such as lightheadedness), seeing a doctor is a smart decision, even if you believe you have anxiety.
But feeling like you're going to faint is often a symptom of anxiety, especially if you suffer from panic attacks.
When you suffer from anxiety, feeling faint is almost exclusively caused by hyperventilation. Also known as "over-breathing," hyperventilation occurs when you unintentionally breathe out too much carbon dioxide as a result of unhelpful breathing habits.
Interestingly, hyperventilation feels like the exact opposite - when you're hyperventilating, it often feels as though you're not getting enough oxygen. So those that are hyperventilating have a tendency to try to take even deeper breaths - breathing in more oxygen to compensate.
This makes it worse. The abundance of oxygen and the depletion of CO2 causes your blood vessels to constrict, which reduces blood flow to the brain. When your brain doesn't feel like it's getting enough blood to your brain, it responds by dropping you to the floor, because the easiest way to make sure blood flow reaches your brain is when you're on the the ground.
Of course, when people hear that their brain isn't getting enough blood, they get worried. Rest assured that feeling faint from anxiety isn't dangerous in the slightest, and can't cause any long-term health issues.
That said, if you are fainting regularly you should make sure that you see a doctor to rule out medical issues. Also, while fainting is not in itself unsafe, although fainting in dangerous places can put you at risk for hitting your head on sharp objects, and feeling faint while driving can impair driving ability.
Hyperventilation is caused by breathing changes - breathing changes that are extremely common in those with anxiety. The most well-known type of hyperventilating occurs during moments of intense panic, when you find yourself breathing in and out at a fast rate.
But that's not the only way that people hyperventilate. You may also simply be breathing at a rate that is too shallow. This is especially true of those that tend to breathe through their chests - a common issue with those that have anxiety.
Also, many people with anxiety think about their breathing. When you focus on your breathing, you start to consciously control it. Your body doesn't need that much oxygen, and often takes very small, slow breaths to compensate. So small and so slow that those that think about their breathing often take deeper breaths than they need. This also can cause hyperventilation.
Another cause of fainting comes from phobias. For example, there are those that faint at the sight of a needle or blood. This type of fainting is known as vasovagal syncope. It involves a sudden and rapid loss in blood pressure that causes the person to immediately drop to the ground as a result.
Fascinatingly, only blood, needles, and a fear of injury are linked to this type of fainting. Other types of phobias are associated with an increase in blood pressure, where fainting is unlikely.
Overheating (hot showers after exertion can cause faint).
Standing up too quickly (can cause low blood pressure to the brain).
Remember, there's no harm in seeing the doctor if you're concerned. Your doctor can easily rule out most of the dangerous causes of feeling faint. But it is an anxiety symptom. If you have reason to believe you're suffering from anxiety, it's highly likely that your experience is the result of hyperventilation.
If you're feeling faint, the first step is to go against your instinct and try not to take in more air than you can handle. You need to add more CO2 to your bloodstream. You can do this by taking slower breaths and trying to breathe in through your stomach, rather than your chest. Also, once you've breathed in, hold your breath for a few seconds before slowly exhaling.
Often you'll notice your feeling faint comes with other symptoms as well. All of these symptoms represent signals that your body is giving you about your anxiety.
Pay attention to these symptoms, and if you believe you have severe anxiety, seek treatment. Anxiety disorders are a highly treatable condition. But only a fraction of those with anxiety seek some type of treatment. Between cognitive behavioral therapy, medications, and self-help, managing your anxiety is possible. You just need to take the first step.
Diehl, Rolf R. "Vasovagal syncope and Darwinian fitness." Clinical autonomic research 15.2 (2005): 126-129.