Need more info
can be caused by many problems, some realtively "benign" and some serious.
Of course, true syncope is scary adn can cause injury. If you have a dysrhythmia, that is a likely cause depending on what kind. Other causes of syncope can be determined by the evals, but also consider medications, seizures, and just straightforward faints (vasovagal syncope) - which can happen for many reasons.