Anxiety is really just a form of stress. It can be experienced in many different ways — physically, emotionally, and in the way people view the world around them. Anxiety mainly relates to worry about what might happen — worrying about things going wrong or feeling like you’re in some kind of danger.
Anxiety is a natural human reaction, and it serves an important biological function: It’s an alarm system that’s activated whenever we perceive danger or a threat. When the body and mind react, we can feel physical sensations, like dizziness, a rapid heartbeat, difficulty breathing, and sweaty or shaky hands and feet. These sensations — called the fight–flight response — are caused by a rush of adrenaline and other stress hormones that prepare the body to make a quick getaway or “flight” from danger.
The fight–flight response happens instantly. But it usually takes a few seconds longer for the thinking part of the brain (the cortex) to process the situation and evaluate whether the threat is real, and if so, how to handle it. When the cortex sends the all-clear signal, the fight–flight response is deactivated and the nervous system starts to calm down.