Why Do I Make Worse Decisions When I'm Stressed?

You know not to answer a tense email at eleven at night, and you answer it anyway. In the morning you reread what you sent and cannot reconstruct the reasoning behind it.

Decisions get worse under stress because stress chemistry weakens the prefrontal cortex, which holds information in mind, weighs options, and holds back impulses, while faster habitual responses get stronger (Arnsten, 2009). The shift occurs even with mild uncontrollable stress, depends on the task (Starcke and Brand, 2012), and reverses as stress eases (Liston, McEwen and Casey, 2009).

What Does the Prefrontal Cortex Do?

The prefrontal cortex sits at the front of the brain, behind the forehead. The neuroscientist Amy Arnsten describes it as the region that provides top-down guidance of thought, behavior, and emotion, and as the brain region most sensitive to the harmful effects of stress (Arnsten, 2009). In practice it lets you hold a few pieces of information in mind at once, compare options, picture consequences, and stop yourself from acting on the first impulse.

It works in constant exchange with the amygdala, the structure behind the detection step that Why Do I React to an Email Before I've Finished Reading It? describes.

Why Does Stress Weaken the Prefrontal Cortex?

Stress raises the levels of two signaling chemicals, norepinephrine and dopamine, in the prefrontal cortex. At moderate levels they support prefrontal function. At the higher levels released during stress, they weaken the connections between prefrontal neurons that hold information in mind, and Arnsten reports that even quite mild stress can produce a rapid loss of prefrontal abilities when the stress is uncontrollable (Arnsten, 2009). Most of the mechanism work she reviews was done in monkeys and rats; the human evidence comes from the behavioral and imaging studies below.

At the same time, stress strengthens the amygdala and the circuits that run habitual responses (Arnsten, 2009).

Controllability matters in the human data as well. Across 208 laboratory studies, having no control over the outcome combined with being judged by others produced the largest cortisol responses (Dickerson and Kemeny, 2004), the trigger described in What Does Fight or Flight Mean at Work?.

Why Do Stressed People Fall Back on Old Habits?

One study showed the habit shift directly. Lars Schwabe and Oliver Wolf stressed some participants with ice water and an observer while others did a warm-water version unobserved. Everyone then learned two actions that each earned a different food, and then ate one of the foods until they no longer wanted it. Unstressed participants shifted away from the action that produced that food, and stressed participants kept performing both actions at the same rate (Schwabe and Wolf, 2009). Two preregistered attempts to repeat the experiment in 2023 did not reproduce the result, so it stands as one study.

Stress changes how people decide, and whether it helps or hurts depends on the task and the situation; a shift toward automatic processing is one of several explanations the review discusses (Starcke and Brand, 2012). At work the shift looks like reaching for the old template or the usual answer when the situation calls for something new, which is one reason change is hard at work when it arrives during a stressful period.

Does the Effect Wear Off?

Yes, in the human study that tested it. Conor Liston, Bruce McEwen and B. J. Casey studied 20 medical students during a month of preparing for a major exam. Compared with a matched low-stress comparison group, the stressed students were worse at shifting attention between tasks, and brain scans showed weaker coordination within a frontoparietal attention network (Liston, McEwen and Casey, 2009). After a month of reduced stress the differences had disappeared, in the task performance and in the brain measures. The sample was small and made up of healthy adults, so the finding says nothing about clinical conditions or about years of severe stress.

What Helps You Decide Well under Stress?

Make the good decision the practiced response before the pressure arrives. Peter Gollwitzer reviewed a planning form he called implementation intentions, plans written as "If situation X happens, then I will do Y," and found that they hand control of the behavior to the situation itself, so the planned response is triggered with less deliberate effort in the moment (Gollwitzer, 1999).

Find the part you can control. When you have no control over the outcome, find the part you can influence, such as the timing of your reply, the question you ask next, or the person you consult.

Let a decision that can wait, wait. The stress chemistry rises with the stressor and falls after it (Arnsten, 2009), so a decision made after the stressor has ended has more prefrontal function available.

What the Prefrontal Cortex Is

Prefrontal cortex: the region at the front of the brain that supports holding information in mind, planning, weighing consequences, holding back impulses, and directing attention. It is the brain region most sensitive to stress, and in the human evidence available its function recovers as the stress passes (Arnsten, 2009; Liston, McEwen and Casey, 2009).

What Does the Popular Version Get Wrong?

The popular account says stress makes people stupid, or that willpower is a tank that runs dry. The research above describes a shift in which brain systems are in control, which depends on whether the stressor can be controlled (Arnsten, 2009) and on the task, so that stress improves performance on some tasks and worsens it on others (Starcke and Brand, 2012). Whether willpower runs out is a separate question with its own contested evidence.

Before your next stressful week, write two if-then rules for decisions you tend to regret under pressure, for example "If a message makes my heart race, then I draft my reply and send it after my next break," and put them where you will see them.

FAQ

Why can't I think clearly when I'm stressed?

Because stress raises norepinephrine and dopamine in the prefrontal cortex to levels that weaken the connections which hold information in mind and weigh options (Arnsten, 2009). At the same time the amygdala and the circuits for habitual responses get stronger, so behavior shifts toward faster, practiced responses and careful thinking takes more effort.

Why do I fall back on old habits when I'm stressed?

In one experiment, stress shifted behavior from goal-directed control toward habit. Stressed participants kept performing an action after its reward no longer mattered to them, while unstressed participants adjusted (Schwabe and Wolf, 2009). Two preregistered replications did not reproduce that result, so the experiment stands as one study.

Can chronic stress permanently damage the prefrontal cortex?

The human evidence available points to recovery in healthy adults after a month of stress. Twenty medical students who showed weaker prefrontal attention function during a month of exam stress recovered to the level of the comparison group after a month of reduced stress (Liston, McEwen and Casey, 2009).

How can I make better decisions under pressure?

Plan in advance. If-then plans, called implementation intentions, link a specific situation to a specific response, so the response is triggered with less deliberate effort (Gollwitzer, 1999). Writing the rules before a stressful period gives you a ready response for the moment when prefrontal control is weaker.

Related Posts:

What Does Fight or Flight Mean at Work?

Why Do I React to an Email Before I've Finished Reading It?