The Upside of Stress: Why Stress Is Good for You, and How to Get Good at It
by Kelly McGonigal
Avery, 2015 ($26.95)

Correlation does not imply causation. This is a fundamental lesson psychology professors like me teach in introductory courses. Violating this principle can lead to serious misconceptions, even dangerous practices.

McGonigal, a psychology instructor at Stanford University, probably teaches that principle, but in The Upside of Stress she seems to have ignored it. The book is a follow-up to a powerful TED talk she gave in 2013, which has had more than 10 million views online. Her message: I have been wrong in counseling people to avoid stress; new research shows that stress can hurt you only if you believe it can.

McGonigal credits a 2012 study by Whitney P. Witt, then at the University of Wisconsin–Madison, and her colleagues for her epiphany, but that study showed only that believing one's stressful experiences are harmful was correlated with illness and early mortality. That does not mean beliefs caused illness. There is a simpler, less mysterious way of accounting for the results: people who experience stress but who suffer minimal ill effects from it come to believe that stress cannot hurt them, whereas people who do suffer ill effects come to believe that stress is harmful. Voilà, we now have the correlation those researchers found but with belief as an outcome rather than a cause. McGonigal continues to make this type of error throughout her book.

On the plus side, she describes a variety of recent experiments that indicate that telling people about the positive aspects of stress can indeed cause some to feel and function better. Even here, though, she often exaggerates the significance of the studies' results by using language suggesting that all the subjects in the study—mothers, students, women—were helped. That never happens in real research; only some people are helped—enough to get the study published.

Based in part on studies with soldiers and police, McGonigal also tells us that avoiding stress can hurt you, whereas high stress can be good for you. She never mentions the many professions in which one must be relaxed to perform optimally: acting, writing and public speaking, to name a few. It makes you wonder: if optimal performance can be achieved when one is in a relaxed state (think martial arts), wouldn't that be the happiest and healthiest way to go through life?

As early as the 1950s, therapists such as the late Albert Ellis showed that teaching people how to reinterpret challenging events in positive ways could help them reduce or eliminate stress, and therapists worldwide now teach people to “reframe” in this way. McGonigal is saying that when you do feel stress, don't make matters worse by stressing about that. Reframe the stress as “excitement” and make it work for you.

Although this strategy might work for some, there are still thousands of studies showing the ill effects of stress on the immune system, mood, the brain, sleep, sexual functioning, you name it. If some people feel and function better when we tell them stress is good, I'm all for it. But stress is still a killer.