This Is Why People Faint at the Sight of Blood

It could have something to do with an overachieving vagus nerve

Illustration: Amber Vittoria

One afternoon when she was six years old, Kim Petschek was walking home from school when she stubbed her toe on the sidewalk, resulting in a small — but bloody — gash. The next thing she remembers is waking up on the street, sprawled out face-first on the concrete with her front…