Fainting Frightens, But Is Usually Benign

People have been swooning for joy since at least the 13th Century when the earliest recorded use of the word can be found. By the 20th Century, losing consciousness for love and rapture was a necessary attribute of a Southern belle. Even today, swooning has a positive connotation, defined as, “a few steps beyond being happy, but not so over the top that you scare children.” But change the language describing the same loss of consciousness and "blacking out like a light" is not so glamourous. Parents fainting with a thud on the floor most certainly gives the kids a fright. But how dangerous is fainting? And how common a problem is it?