Just about everyone feels anxious at some point in their lives.
The butterflies in the stomach at the thought of an upcoming speech; the dry mouth and pounding heart during a big presentation.
We've all been there.
The body causes these perfectly normal physical responses to keep us alert and responsive to changes in the environment.
However, when the anxiety and symptoms of anxiety start affecting your life; when you find yourself avoiding situations where you are likely to panic, that is when the normal physiological response crosses the line to become an anxiety disorder.
Anxiety is not a single disorder with a clearly defining characteristic.
It is actually an umbrella term that encompasses a diverse group of anxiety disorders.
Each anxiety disorder has its own symptoms and patient profile.
However, all the anxiety disorders have one characteristic in common ' they involve the patient feeling worried or frightened in situations where most people would not feel alarmed.
For example, people who suffer from generalised anxiety disorder simply have a vague dread, a feeling that something will go wrong without any reason to feel this way.
People who are obsessive-compulsive may feel a nagging worry about certain things, or have certain recurrent behaviours ' most famously, washing their hands over and over or not being able to abide a single thing out of place.
Phobias also fall under this category, where the patient feels an irrational, extremely strong fear of something that is usually considered quite ordinary.
A patient with social anxiety disorder may be seen as being extremely shy, as they fear being humiliated in public and thus rarely venture into social situations.
As anxiety is an emotional problem that evokes a physical reaction, there are both emotional and physical symptoms.
Emotional symptoms include feelings of dread, trouble concentrating, restlessness and jumpiness, constantly being on guard for danger, and episodes where the patient's mind blanks out.
Physical symptoms include the classic pounding heart, stomach discomfort, and sweating that anyone who has done something unnerving has experienced, but also include dizziness, headaches, tiredness, insomnia, muscle tension, and shortness of breath.
Some people suffer from panic or anxiety attacks, where the person suddenly becomes completely overwhelmed by terror for a short but frightening period of time.
During this time, the physical symptoms become exacerbated, resulting in hyperventilation, hot flashes or cold chills, uncontrollable shaking, nausea, muscle weakness, and generally a feeling of being about to faint.
Just a week ago, I was talking to a person in a position of authority, and she started asking questions about a project I had done a while ago.
Although I knew the project inside and out, I was not expecting her to ask questions about it, and I had a panic attack ' cold sweat, nausea, trembling, my vision graying out and spots flashing in front of my eyes.
Somehow I answered her questions, though definitely not as well as I could have done, and stumbled away to sit down before I fell down.
I am not sure if she did not notice my distress, or if I was really that good at hiding it.
Sometimes panic attacks have clear triggers, like the one I had last week.
Being attacked, for example, or just having to answer some questions unexpectedly, may be enough to do it.
However sometimes they just appear out of nowhere, which is possibly even more frightening.
It is not uncommon for sufferers of panic attacks to actually become afraid of having the panic attack, causing even more stress to the patient.