Where is a fainting couch when you need one? Michael C. Gray/From www.shutterstock.comOver one million Americans faint every year, and countless more do worldwide. Fear, pain, the sight of blood or prolonged standing – think the long lines of summer travel – can trigger fainting. These triggers set off a reflex in our nervous system that cause our hearts to paradoxically slow instead of speed up, and our blood vessels to dilate instead of constrict. Blood pressure and brain blood flow plummet, a