A panic attack can be described as an exaggeration of the body’s normal response to fear, stress or excitement.
The body is filled with a rapid build-up of overwhelming sensations, such as a pounding heartbeat, feeling faint, sweating, nausea, chest pains, breathing discomfort, feelings of losing control, shaky limbs and legs turning to jelly.
When this happens it is very common to think that you are going mad or that you are about to black out, or even have a heart attack.
You may even feel like you are going to die in the course of the attack, and this makes it very terrifying.
Panic attacks usually come on very quickly, symptoms usually peaking within 10 minutes.
Most panic attacks will last for between 5 and 20 minutes.
Some people report attacks lasting for up to an hour, but they are likely to be experiencing one attack after another or a high level of anxiety after the initial attack.
You may have one or two panic attacks and never experience another.
Or you may have attacks once a month or several times each week.
For some people they seem to come without warning and strike at random.
Panic attacks can also come in the night and wake you up.
These night-time attacks occur if your brain is on 'high alert' (due to anxiety) and can detect small changes in your body which it then interprets as a sign of danger.
Night-time attacks may be particularly frightening, as you may feel confused and are helpless to do anything to spot them coming.