Writing about your most important values before a stressful event has lowered stress responses in several studies, including cortisol in a lab stress test and stress hormones around a big exam. The effects are modest, the studies are mostly small, and not every study has found a benefit. The evidence is for reflecting on what you value, not for repeating positive statements about yourself.
What “affirmation” means in these studies
In stress research, an affirmation is not a line like “I am calm and in control.” It’s a short exercise, usually writing, in which you pick a value that matters to you, such as your family, your friendships, creativity or faith, and reflect on why it matters (Cohen & Sherman, 2014). The thinking behind it, from self-affirmation theory, is that stress often comes from a threat to how we see ourselves: being judged, failing, looking foolish. Reminding yourself of what you value widens your view of yourself, so one threat stops feeling like everything.
What the studies found
Lower cortisol in a lab stress test
In the best-known study, 85 people completed either a values-affirmation task or a control task before a stressful lab challenge. Those who had affirmed their values had significantly smaller rises in cortisol, a hormone the body releases under stress. How much less stressed they felt depended on their personal resources: people with high self-esteem and optimism who affirmed their values reported the least stress (Creswell et al., 2005).
Steadier stress hormones before an exam
Students wrote two essays about important values over the two weeks before their most stressful exam, while a comparison group did not. In the comparison group, levels of epinephrine (adrenaline) rose from a baseline two weeks earlier to the morning of the exam. In the affirmation group, they didn’t. The effect was strongest in the students who were most worried about being judged negatively at college (Sherman et al., 2009).
Clearer thinking under pressure
Eighty students worked on 30 hard word puzzles against the clock while being watched by an evaluator. Affirming their values beforehand improved problem-solving for students who were chronically stressed and otherwise tended to underperform (Creswell et al., 2013).
Inside the brain
In a brain-scanning study, people alternated between affirmation and control blocks before stressful tasks. After affirming, they reported less stress and performed better. Affirmation increased activity in a brain region linked to reward and value, and was followed by less activity in a region tied to threat responses during the stress task (Dutcher et al., 2020).
A newer test, with a twist
A 2025 study ran two experiments with university students. Before a performance stressor (a public-speaking and mental-arithmetic test), writing about values lowered cortisol, heart rate and felt stress compared with a control group, while emotional support didn’t. Before an interpersonal stressor, both helped, but emotional support helped more (Wang et al., 2025). The authors concluded that value affirmation is better suited to performance stress, and emotional support to stress about how others treat you.
Where it didn’t help
In one study, writing about values before a stressful speech did not reduce anxiety, either beforehand or afterward, compared with neutral writing (Czech, Katz & Orsillo, 2011).
How strong is the evidence?
Promising, but modest. Here is a fair reading:
- The studies are small. Most have tens of people per group. Small studies can overestimate effects, and findings from them need repeating.
- Results are mixed. Several studies show lower stress responses, but at least one found no change in anxiety.
- Effects are small on average. A 2025 meta-analysis of 129 tests found small but significant benefits of self-affirmation for well-being in general populations, and the benefits lasted beyond the moment (Zhang et al., 2025).
- Big effects in one setting don’t always carry over. In schools, large replications of affirmation exercises have sometimes found no effect at all (Hanselman et al., 2017).
- Who benefits varies. The biggest effects tended to show up in people under the most pressure: the most worried students, the chronically stressed.
So it’s reasonable to try a values affirmation before a stressful event, because it’s quick, free and low-risk. It’s not reasonable to expect it to replace other ways of managing stress.
Why it might work
The leading idea is perspective. A stressful event, like a job interview or a hard medical appointment, can feel like a test of your whole worth. Reflecting on something else you care about reminds you that you’re more than this one moment. In experiments, affirmation made a threatened part of the self feel less all-defining, and that broader perspective explained the drop in defensiveness (Critcher & Dunning, 2015). The brain findings fit too: activity in reward and value regions, with less in threat regions (Dutcher et al., 2020).
This is also why the type of affirmation matters. Repeating a statement you don’t believe, like “I am totally relaxed,” can make you more aware of the gap. In one study, people with low self-esteem felt worse after repeating “I’m a lovable person” (Wood, Perunovic & Lee, 2009).
How to use it before a stressful event
A ten-minute values exercise
- Do it shortly before, on the day or in the days leading up. In the exam study, students wrote twice in the two weeks before.
- Pick a value that has nothing to do with the stressor. If the stress is a work presentation, choose friendship, faith, family, humor or creativity.
- Write for about ten minutes. Why does this value matter to you? When did you last act on it?
- Keep one line. For example: “I care about being a good friend. That’s true however this interview goes.”
Here’s what a few minutes of writing might look like the night before a job interview:
The thing I care about most is being a good brother. When Leo was struggling last spring, I called him every Sunday, even when I didn’t know what to say. He told me later it helped. Tomorrow’s interview matters, but it isn’t the measure of me. This is.
It doesn’t mention the interview much, and that’s the point. You’re reminding yourself of the parts of your life the interview can’t touch.
In the moment
- Talk to yourself as “you.” People who reflected on a stressful speech using their own name or “you,” rather than “I,” were less distressed and were rated as giving better speeches (Kross et al., 2014). “Okay, Jess, you’ve prepared. First slide, slowly.”
- Treat the racing heart as fuel. People told to see their stress arousal as functional and helpful showed healthier cardiovascular responses during a stressful task and paid less attention to negative information (Jamieson, Nock & Mendes, 2012). “This is my body getting ready.”
- Make an if-then plan. “If my mind goes blank, then I’ll look at my notes and take a breath.” Plans like this had a medium-to-large effect on reaching goals across 94 tests (Gollwitzer & Sheeran, 2006).
Lines for stressful moments
These borrow from values and stay believable:
- I care about doing this well, and that’s why I’m nervous.
- Whatever happens in there, what I care about doesn’t change.
- I can be scared and still be someone who shows up.
- One bad moment doesn’t cancel who I am.
- I’ve prepared what I can. The rest I’ll handle as it comes.
For more, see our affirmations for anxiety and affirmations for work.
What it won’t do
A values exercise won’t fix a job that’s burning you out, a relationship that’s hurting you, or an anxiety disorder. If stress or anxiety affects your sleep, health or daily life for weeks, talk to a doctor or therapist; affirmations can sit alongside care, not replace it. If you’re struggling or thinking about harming yourself, you can call or text 988 in the US (Suicide & Crisis Lifeline), or find a helpline in your country at findahelpline.com.
The short version
- Writing about your values before a stressful event lowered cortisol, stress hormones or felt stress in several studies.
- The evidence is modest: small studies, small average effects, and at least one null result.
- It seems to help most for people under real pressure, and for stress about performing and being judged.
- Use it as a short exercise before the event, then use distanced self-talk, a helpful view of your nerves, and an if-then plan in the moment.