When you feel under threat, anxiety sets off the release of a  hormone called adrenaline. This causes your heart to beat faster to carry blood where it's most needed. You breathe faster to provide the extra oxygen required for energy. You sweat to prevent overheating. Your mouth may feel dry, as your digestive system slows down to allow more blood to be sent to your muscles. Your senses become heightened and your brain becomes more alert.

 

These changes are designed to make your body take action and protect you in a  dangerous situations, either by running away or fighting. It is known as the 'fight or flight' reflex. Once the danger has passed, other hormones are released, which may cause you to shake as your muscles start to relax. This response is useful for protecting you against physical dangers; for example, it can help you run away from wild animals, attackers, fires etc. The response is not so useful if you want to run away from exams, job interviews or a driving test. This is because, if there is no physical threat, and you have no need to physically run away or fight, the effects of adrenaline subside more slowly, and you may go on feeling agitated for a long time.

 

If the anxiety stays at a high level for a long time, you may feel that it is difficult to deal with everyday life. The anxiety may become severe; you may feel powerless, out of control, as if you are about to die or become mad. Sometimes, if the feelings of fear overwhelm you, you may experience a panic attack. A panic attack is an exaggeration of the body’s normal response to fear, stress or excitement. It is the 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. If you experience this, you may fear that you are going mad, blacking out, or having a heart attack. You may be convinced you are going to die in the course of the attack – making this a terrifying experience.