Affirmations can work, but modestly, and the best evidence is for one kind: reflecting on what you value, which has small but measurable effects on stress, defensiveness and follow-through. Repeating bold positive statements about yourself has much weaker support, and for people with low self-esteem it can backfire.
First, what counts as an affirmation?
The word covers at least three different things, and the research on each is different:
- Positive self-statements. Lines like “I am confident” or “I’m a lovable person,” said or repeated. This is what most people picture.
- Values affirmation. The psychologists’ version. You pick something that matters to you, like your family, honesty or being creative, and write or think about why it matters. In research papers, “self-affirmation” almost always means this (Cohen & Sherman, 2014).
- Self-talk and plans. The short instructions and encouragement you give yourself in the moment (“slow down, breathe out”), and plans like “when my alarm goes off, I’ll get up before I check my phone.”
So when someone says “studies show affirmations work,” it’s worth asking which kind they mean.
The evidence for reflecting on your values
Self-affirmation theory comes from the psychologist Claude Steele (Steele, 1988). The idea is that people need to see themselves as basically good and capable. When something threatens that picture, like a poor grade, a health warning or being judged, people get defensive and stressed. Reflecting on other things you care about widens the frame, so the threat feels less like a verdict on your whole self (Cohen & Sherman, 2014).
Findings that have held up reasonably well:
- Less defensiveness about health advice. A meta-analysis of 144 experimental tests found that people who did a self-affirmation before reading health-risk information were a little more likely to accept the message, to plan to change, and to actually change their behavior. The effects were small, but similar in size to those of other health-behavior interventions (Epton et al., 2015).
- Lower stress responses, in some studies. In one lab study, 85 people did either a values task or a control task before a stressful challenge. Those who affirmed their values had lower cortisol responses (Creswell et al., 2005). In another, students who wrote two essays about their values in the two weeks before their most stressful exam didn’t show the rise in the stress hormone epinephrine that the comparison group showed (Sherman et al., 2009).
- Small gains in well-being. A 2025 meta-analysis of 129 tests from 67 published articles found small positive effects on how people saw themselves and on their general and social well-being, in people from the general population rather than patients (Zhang et al., 2025).
That’s not nothing. It’s also not life-changing. A fair summary is: small effects that show up across many studies, under the right conditions.
Why positive affirmations don’t work for some people
The best-known test of repeating a positive statement is not encouraging. Psychologists asked people to repeat “I’m a lovable person.” People with high self-esteem felt a little better afterward. People with low self-esteem felt worse than similar people who didn’t repeat it (Wood, Perunovic & Lee, 2009). One likely reason: when a line is far from what you believe about yourself, saying it brings the counterevidence to mind.
A second problem is what many affirmations describe. The psychologists Gabriele Oettingen and Doris Mayer separated expectations (judging that a good outcome is likely) from fantasies (enjoying images of a dream future). In studies of graduates looking for jobs, students, and patients having hip-replacement surgery, positive expectations predicted more effort and better results weeks or months later, while positive fantasies predicted the reverse (Oettingen & Mayer, 2002). An affirmation that describes a finished dream, like “I am wealthy and successful,” may work more like a fantasy than a plan.
Picturing the work looks more useful. In one study, college students who spent the days before a midterm mentally rehearsing how they would study ended up studying more and getting better grades (Pham & Taylor, 1999).
Who affirmations seem to help most
Across these studies, a pattern shows up: values affirmations tend to help most when someone is under real pressure.
- In the exam study, the stress-buffering effect was strongest in the students most worried about being judged negatively at college (Sherman et al., 2009).
- Affirming values improved problem-solving under time pressure, in front of an evaluator, for chronically stressed students who were otherwise underperforming (Creswell et al., 2013).
- In classrooms, a meta-analysis of 58 studies found a small average benefit for students facing threats tied to their social identity, such as negative stereotypes about their group, and essentially none for other students (Wu, Spreckelsen & Cohen, 2021).
For positive self-statements, the pattern ran the other way: they helped, a little, the people who already felt good about themselves (Wood, Perunovic & Lee, 2009).
Do affirmations change your brain?
You may have read that affirmations “rewire your brain.” The real findings are narrower. In brain-scanning studies, people who reflected on their core values showed more activity in areas involved in thinking about yourself and in reward and value, and that activity predicted later behavior change, such as becoming less sedentary (Cascio et al., 2016; Falk et al., 2015). That tells us what happens in the brain during a values exercise. It doesn’t show that repeating a phrase permanently changes how your brain works.
Where the evidence is shaky
Results that look strong in one study don’t always survive being repeated. A famous 2006 study found that a brief in-class writing exercise about values improved the grades of African American students and narrowed the racial achievement gap by 40% (Cohen et al., 2006). But when another team repeated a values affirmation at scale, with the same procedures, in a setting where it had worked before, they found no effect (Hanselman et al., 2017). An attempt in two new schools also found none (Protzko & Aronson, 2016). A follow-up of a district-wide rollout found benefits that depended on the school and on how much students engaged with the writing (Borman et al., 2018).
The lab stress studies are mostly small, and they don’t all agree. In one, writing about values did not reduce anxiety before or after a stressful speech (Czech, Katz & Orsillo, 2011).
So the honest answer is: real effects, smaller and more fragile than most articles about affirmations suggest.
How to give affirmations a fair chance
- Lead with values, not verdicts. “I care about being a steady parent” is something you can stand behind on a bad day. “I am a perfect parent” isn’t.
- Make them believable. True today, or true as work in progress: “I’m learning to…”, “I can…”. If you wouldn’t sign your name under a line, soften it until you would.
- Name the work, not just the prize. “I’ll practice my opening twice before lunch” gives you something to do. “I am a brilliant speaker” doesn’t.
- Attach a plan. Plans in an if-then form (“When I sit down at my desk, I’ll start with the hardest email”) had a medium-to-large effect on reaching goals across 94 tests (Gollwitzer & Sheeran, 2006).
- Try “you” instead of “I”. In a set of studies, people who reflected on their feelings before a stressful speech using their own name or “you” were less distressed and were rated as giving better speeches (Kross et al., 2014).
- Use them when something is at stake. Affirmation seems to do the most just before something that tests you: the exam, the appointment, the hard conversation.
Affirmations are a small tool, not a treatment. If low self-esteem or low mood weighs on you most days, a doctor or therapist can help more than any list of lines. 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
- Values affirmations have the best evidence. Writing or thinking about what matters to you has small, measurable effects on stress, defensiveness and health behavior, especially under pressure.
- Positive self-statements have little direct support. Lines you don’t believe can leave you feeling worse.
- Single studies don’t always replicate. Expect a nudge, not a transformation.
- Write lines you can believe, rooted in your values and tied to a specific moment. If you want a starting point, our morning affirmations are written this way, and so is our list of affirmations for confidence.