Unlike phobias (which are linked to a particular situation) panic attacks can occur at any time in almost any situation, for example; at home, when driving, during social events, in public places, or in bed during the night or the early morning. Because of this unpredictability sufferers often find it hard to understand the underlying cause of their symptoms, and may start to fear that they have a serious physical illness (such as a heart problem or cancer) or, perhaps, that they are losing their sanity (going "crazy" or "mad"). This, in turn, may lead to fears of dying, or collapsing, or losing control in public places, and anxiety about being alone or leaving the safety of home

Although they seem random and unpredictable, panic attacks have a simple and logical explanation . They are caused by excessive surges of adrenaline - a hormone produced quite naturally by the body in response to situations when we feel threatened by events. Adrenaline helps to arouse our bodies, and gives us the energy to deal with a crisis in our lives. However, if the crisis goes on for a long time (weeks or months) our bodies become accustomed to producing higher levels of adrenaline and, when the crisis is over, these levels do not drop immediately but may remain high for several days, or even weeks afterwards. This extra energy may discharge itself in panic attacks with all the frightening physical symptoms.

If these symptoms are then seen as signs of serious physical or psychological illness, this creates a new crisis leading to further increases of adrenaline which, in turn, leads to more panic attacks and physical symptoms. In this way the sufferer becomes locked into a vicious circle which may prolong the symptoms for many weeks or months.