Hyperventilation
Hyperventilation, or over breathing, is when we breathe faster and/or deeper than necessary, and causes light-headedness and other undesirable symptoms often associated with panic attacks.
In fact, the most common causes are stress or anxiety of what is otherwise known as hyperventilation syndrome.
Yes, hyperventilation is, you are right, breathing more air per minute (usually at rest) than the medical norms. The values for normal minute ventilation (or respiratory minute volumes) at rest for a 70-kg person range from 4-6 L/min for older physiological textbooks and up to 6-9 L/min for some modern textbooks. Modern people and people with chronic diseases breathe much more than that: What is hyperventilation
Therefore, it is not something that medical sources lie to us about. For example, it may have nothing to do with light headedness or feeling dizzy. One can simply breathe 2-3 times more than the norm all his life. This is what most modern people do.
Symptoms of hyperventilation are numerous and they range from asthma attacks, constipation and coughing to nasal congestion and muscle cramps. All these symptoms are immediately relieved with breathing less.