Amid all the recent research on — and criticism of — positive thinking, one question hasn't received much attention: does optimism actually make people healthier, or is it the other way around?

According to Barbara Ehrenreich's Bright-Sided, the much-vaunted "power of positive thinking" won't cure cancer, make us rich, or necessarily even keep us happy. In fact, it may be harming us.

Barbara Ehrenreich is looking through a half-empty glass in her new book, Bright-Sided, which takes a critical look at America's culture of positive thinking and explains how this seemingly innocuous coping tactic is actually damaging our society.

According to new research, optimistic women live longer, and have overall better health, than their pessimistic peers. Researchers also reported that "cynically hostile" women were at a higher risk of dying during the eight-year study. [LiveScience]

Perhaps unsurprisingly for anyone who's ever tried to pull herself out of a funk by chanting affirmations at her mirror, such positive self-talk might actually lower some people's self-esteem.