People with panic disorder have feelings of terror that strike suddenly and usually last for several minutes. They misinterpret harmless symptoms, like a racing heart and dizziness, as a sign that they might die or go mad, for example. This, in turn, produces more anxiety and physical symptoms. Panic attacks can even start while the person is asleep. Panic disorder can lead to phobias when the sufferer avoids situations in which they previously suffered a panic attack, and often occurs with agoraphobia. It is twice as common in women as in men.