Panic Attack is a spontaneous, unprovoked, unpredictable sudden fear or dread for which there is no apparent trigger. And if there is a trigger, it is usually insignificant, but the result is a sudden release of large quantities of Norepinephrine, Adrenaline, and other chemicals. In fact the same biochemical that occurs in the brain during Fight or Flight (a normal response) occurs in spontaneous panic attacks (abnormal response).