Reflex syncope is a brief loss of consciousness due to a neurologically induced drop in blood pressure and/or a decrease in heart rate.

Before losing consciousness, the individual frequently experiences early signs or symptoms such as lightheadedness, nausea, the feeling of being extremely hot or cold (accompanied by sweating), ringing in the ears, an uncomfortable feeling in the heart, fuzzy thoughts, confusion, a slight inability to speak or form words (sometimes combined with mild stuttering), weakness and visual disturbances such as lights seeming too bright, fuzzy or tunnel vision, black cloud-like spots in vision, and a feeling of nervousness can occur as well.

If 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.

[citation needed] The autonomic nervous system's physiological state (see below) leading to loss of consciousness may persist for several minutes, so Reflex syncope occurs in response to a trigger due to dysfunction of the heart rate and blood pressure regulating mechanism.

The core of the diagnosis of vasovagal syncope rests upon a clear description of a typical pattern of triggers, symptoms, and time course.

[citation needed] In people with recurrent vasovagal syncope, diagnostic accuracy can often be improved with one of the following diagnostic tests: Treatment for reflex syncope focuses on avoidance of triggers, restoring blood flow to the brain during an impending episode, and measures that interrupt or prevent the pathophysiologic mechanism described above.

[citation needed] Types of long-term therapy for vasovagal syncope include[18] Brief periods of unconsciousness usually cause no lasting harm to health.

[citation needed] The main danger of vasovagal syncope (or dizzy spells from vertigo) is the risk of injury by falling while unconscious.