<unk> s are sudden, discrete periods of intense anxiety, fear and discomfort that are associated with a variety of somatic and cognitive symptoms. The onset of these episodes is typically abrupt, and may have no obvious trigger. Although these episodes may appear random, they are considered to be a subset of an evolutionary response commonly referred to as fight or flight that occur out of context, flooding the body with hormones <unk> rticularly adrenalin) that aid in defending itself from harm. 
According to the American Psychological Association the symptoms of a<unk>  commonly last approximately ten minutes. However,<unk> s can be as short as 1-5 minutes, while more severe<unk> s may form a cyclic series of episodes, lasting for an extended period, sometimes hours. Often those afflicted will experience significant anticipatory anxiety in between attacks and in situations where attacks have previously occurred.<unk> s also affect people differently. Experienced sufferers may be able to completely 'ride out' a<unk>  with little to no obvious symptoms. Others, notably first time sufferers, may even call for emergency services; many who experience a<unk>  for the first time fear they are having a heart attack or a nervous breakdown. (Wilson 1996)
Panic attack
Heat syncope
Heat stroke
Vasovagal syncope
Drop attack
Defecation syncope
Neurocardiogenic syncope
Micturation syncope