Though the placebo effect remains largely shrouded in mystery, researchers attribute some aspects of the placebo response to active mechanisms in the brain that can influence bodily processes such as the immune response and release of hormones.

CNN: The power of perceptions: Imagining the reality you want

While I go back and forth, I tend to agree that once you get beyond the short term release of endogenous opioids in response to the expectation of pain relief, a mysterious placebo effect that produces all sorts of miraculous effects is far less proven than people think.

FORBES: Harvard Placebo Study Was Seriously Overhyped