The common causes of sudden fainting for a few seconds and waking up fine are mainly epileptic seizures and syncope. An epileptic seizure is an abnormal discharge of cortical neurons in the brain that results in transient brain dysfunction, which can result in impaired consciousness, a few seconds of seizure, a brief blur of consciousness, and no very obvious discomfort upon awakening. Then there is syncope, which is a transient, episodic loss of consciousness due to reduced blood supply to the cerebral hemispheres and brainstem, and the main pathological mechanism is hypoperfusion of the brain and to the brainstem. Syncope is followed by dizziness and headache, but can disappear completely after rest.