Stress, though often psychological, worsens inflammation, apparently part of an ancient biological response to warnings of danger that marshals the body’s resources for recovery. (Another signal of that response: how you just want to rest when you get the flu.) While the threats that trigger this response in prehistory were physical, like something that could eat us, these days the triggers are psychological—an angry spouse, a snarky tweet. Yet the body’s reactions are the same, including emotional upset.
