That’s because stress primes the brain to take automatic action. Any impulse will be harder to control, whether it’s craving Krispy Kremes, or procrastinating on a project. Neuroscientists sometimes say that we have one brain, but two minds: a mind that makes conscious choices, based on self-reflection and awareness; and a mind that makes automatic responses based on instinct and habit.
Each of these “minds” are supported by different neural circuits—different systems of the brain in command of your thoughts, emotions, and actions. Stress selectively inhibits the circuitry of self-awareness and self-control, and activates the circuitry of habit and impulse. Neuroscientists describe it like flicking a switch: stress hormones turn off the reflection mode and turn on the reflex mode. The result: When we’re under stress at work or at home, we find ourselves feeling stuck and out of control. Stress even impairs your brain’s ability to predict the consequences of a choice. So when you’re reaching for that doughnut or shoving aside your project, you think it’s going to make you feel better. Your brain selectively suppresses predictions about feeling remorse afterward. It also suppresses knowledge about the health consequences of eating doughnuts, or the professional costs of procrastinating. It’s not until later that you find yourself wondering, what happened? Why on earth did I give in again? A new study by psychologists at Ruhr University in Germany shows just how powerful stress hormones are at pushing people toward habit. The researchers recruited 40 men and 40 women for a test of how stress influences food choices. First, the researchers gave participants either a placebo or propranolol, a drug that blocks the effects of stress hormones. Then they randomly assigned the participants to either a stress induction (holding their hands in ice-cold water for 3 minutes, which is very painful and reliably triggers a physiological stress response) or a control procedure (holding their hands in comfortably warm water for 3 minutes). So you have some participants stressed out, and some not; and you have some participants “protected” from the neurological effects of stress, and some not. Next, the participants performed an “instrumental learning” food choice task, the details of which are incredibly complex (you can read them all here). But the gist of the task was this: the participants were trained in a computer game that rewarded them with different foods for pressing one button vs. another. Everyone had a preference for one food, and over time they “learned” to press a specific button to get their desired food. In other words, they built a habitual response. After the participants learned this new habit, the researchers forced them to consume so much of it that they became sick of it. Then they gave them the opportunity to choose again between two food rewards. The researchers knew which food the participants wanted now—the participants themselves stated that they had switched their original preferences. The question was: Would stressed-out participants be a slave to habit, and press the button associated with the learned habit, to get the food they were now sick of? Would they find themselves—like so many of do under stress—eating something they didn’t really want, but somehow couldn’t resist? Yep. The participants who were stressed and received a placebo were more likely to act on habit, and press the button to get their now less-desired food. But the participants who were stressed and received the propranolol behaved like non-stressed participants. They broke their habit and made a new choice consistent with their new preferences. I love this study not because of the bad news (stress impairs good decisions), but the good news: changing your stress physiology can help you make smart choices. And it really is good news you can use. You don’t need a drug to block stress hormones; there are much simpler ways to reduce stress hormones and calm a stress response. Things like a few minutes of focused breathing, snuggling with your dog (or favorite human!), or even a funny video on YouTube. If stress has you feeling stuck in old habits, start stockpiling strategies for quick stress relief. You don’t necessarily need to fix all the problems in your life to start making progress in your life. If you can shift your body’s physiology out of emergency mode, you can help your brain remember what it is you really want—and what you need to do to get it. Kelly McGonigal is a psychologist at Stanford University. Her latest book, The Willpower Instinct: How Self-Control Works, Why It Matters, and What You Can Do to Get More of It—to be released December 29th—is full of strategies for mindful and self-compassionate change. Pre-order it here. Study referenced: Schwabe L, Höffken O, Tegenthoff M, Wolf OT (2011). Preventing the Stress-Induced Shift from Goal-Directed to Habit Action with a β-Adrenergic Antagonist. Journal of Neuroscience, 1(47):17317-25.
