the person does not fall into a fully flat, supine position, and the head remains elevated above the trunk, a state similar to a seizure may result from the blood's inability to return quickly to the brain, and the neurons in the body will fire off and generally cause muscles to twitch very slightly but mostly remain very tense. The autonomic nervous system's physiological state (see below) leading to loss of consciousness may persist for several minutes, so If patients try to sit or stand when they wake up, they may pass out again The person may be nauseated, pale, and sweaty for several minutes or hours Causes Reflex syncope occurs in response to a trigger due to dysfunction of the heart rate and blood pressure regulating mechanism. When heart rate slows or blood pressure drops, the resulting lack of blood to the brain causes fainting. Vasovagal Typical triggers include: Prolonged standing Emotional stress Pain The sight of blood Fear of needles Time varying magnetic field (i.e. transcranial magnetic stimulation) Situational After or during urination (micturition syncope) Straining, such as to have a bowel movement Coughing Swallowing Lifting a heavy weight Carotid sinus Pressing upon a certain spot in the neck. This may happen when wearing a tight collar, shaving, or turning the head. Pathophysiology Regardless of the trigger, the mechanism of syncope is similar in the various vasovagal syncope syndromes. The nucleus tractus solitarii of the brainstem is activated directly or indirectly by the triggering stimulus, resulting in simultaneous enhancement of parasympathetic nervous system (vagal) tone and withdrawal of sympathetic nervous system tone. This results in a spectrum of hemodynamic responses: On one end of the spectrum is the cardioinhibitory response, characterized by a drop in heart rate (negative chronotropic effect) and in contractility (negative inotropic effect) leading to a decrease in cardiac output that is significant enough to result in a loss of consciousness. It is thought that this response results primarily from enhancement in parasympathetic tone. On the other end of the spectrum is the vasodepressor response, caused by a drop in blood pressure (to as low as 80/20) without much change in heart rate. This phenomenon occurs due to dilation of the blood vessels, probably as a result of withdrawal of sympathetic nervous system tone. The majority of people with vasovagal syncope have a mixed response somewhere between these two ends of the spectrum. One account