A panic attack is a period of incredibly intense, often temporarily debilitating, sense of extreme fear or psychological distress, typically of abrupt onset. Though it is often a purely terrifying feeling to the sufferer, panic attacks are actually an evolutionary body response often known as the fight-or-flight response occurring out of context. The most common symptoms may include trembling, shortness of breath, heart palpitations, chest pain (or chest tightness), sweating, nausea, dizziness (or slight vertigo), light-headedness, hyperventilation, paresthesias (tingling sensations), and sensations of choking, smothering and dreamlike and disconnected sensations. During a panic attack, the body typically releases large amounts of adrenaline into the bloodstream. First time panic attacks are usually one of the worst experiences of a person's life. Typically, first time sufferers of a panic attack truly believe they are dying, going insane or having a heart attack. Repeated and seemingly unprovoked panic attacks may be a sign of Panic Disorder, but panic attacks are associated with other anxiety disorders as well. For example, people who suffer from phobias may experience panic attacks upon exposure to certain triggers.