<P> Hyperventilation syndrome may occur when a person breathes from the chest, which can lead to overbreathing (exhaling excessive carbon dioxide in relation to the amount of oxygen in one's bloodstream). Hyperventilation syndrome can cause respiratory alkalosis and hypocapnia . This syndrome often involves prominent mouth breathing as well . This causes a cluster of symptoms, including rapid heart beat, dizziness, and lightheadedness, which can trigger panic attacks . </P> <P> Panic attacks may also be caused by substances . Discontinuation or marked reduction in the dose of a substance such as a drug (drug withdrawal), for example an antidepressant (antidepressant discontinuation syndrome), can cause a panic attack . According to the Harvard Mental Health Letter, "the most commonly reported side effects of smoking marijuana are anxiety and panic attacks . Studies report that about 20% to 30% of recreational users experience such problems after smoking marijuana ." </P> <P> People who have repeated, persistent attacks or feel severe anxiety about having another attack are said to have panic disorder . Panic disorder is strikingly different from other types of anxiety disorders in that panic attacks are often sudden and unprovoked . However, panic attacks experienced by those with panic disorder may also be linked to or heightened by certain places or situations, making daily life difficult . </P> <P> Agoraphobia is an anxiety disorder which primarily consists of the fear of experiencing a difficult or embarrassing situation from which the sufferer cannot escape . Panic attacks are commonly linked to agoraphobia and the fear of not being able to escape a bad situation . As the result, severe sufferers of agoraphobia may become confined to their homes, experiencing difficulty traveling from this "safe place". The word "agoraphobia" is an English adoption of the Greek words agora (αγορά) and phobos (φόβος). The term "agora" refers to the place where ancient Greeks used to gather and talk about issues of the city, so it basically applies to any or all public places; however the essence of agoraphobia is a fear of panic attacks especially if they occur in public as the victim may feel like he or she has no escape . In the case of agoraphobia caused by social phobia or social anxiety, sufferers may be very embarrassed by having a panic attack publicly in the first place . This translation is the reason for the common misconception that agoraphobia is a fear of open spaces, and is not clinically accurate . Agoraphobia, as described in this manner, is actually a symptom professionals check for when making a diagnosis of panic disorder . Other syndromes like obsessive compulsive disorder or post traumatic stress disorder and social anxiety disorder can also cause agoraphobia; basically any irrational fear that keeps one from going outside can cause the syndrome . </P>

Breathing slowly in a pattern of 5 seconds in and 5 seconds out triggers a relation response called