What counts as stress in this research?
In everyday speech, stress covers anything from a tight deadline to months of worry. Most of the research below studies something narrower: acute stress, a short, deliberately stressful situation in a laboratory, followed or accompanied by a memory or attention task.
A common method is the Trier Social Stress Test: after a 10-minute anticipation period, the participant gives a speech and does mental arithmetic for 10 minutes in front of an audience [1]. In the studies that validated it, the test reliably raised levels of the stress hormone cortisol two- to four-fold [1]. Another common method is the cold pressor task, in which people hold a hand in ice-cold water [2].
Chronic stress, lasting months or years, is a different question. A review of animal and human research concluded that long-term exposure to stress hormones affects brain structures involved in cognition and mental health, with effects that depend on when in life the exposure happens and how long it lasts [3]. That review describes possible mechanisms; it does not measure how much chronic stress changes memory in a particular person. Most of what follows is about short-term stress.
How stress affects attention and working memory
Working memory is the small mental workspace that holds information while you use it (What is working memory?). It is one of the executive functions, together with inhibition and cognitive flexibility (What are executive functions?).
A 2016 meta-analysis pooled 51 studies with 2,486 participants, mostly young adults without a known psychiatric disorder, that measured these functions after acute stress [4]. It found:
| Function | What the tasks asked | Effect of acute stress |
|---|---|---|
| Working memory (34 studies) | Hold and update information, as in n-back or span tasks | Impaired, a small effect (g = −0.197) |
| Cognitive flexibility (6 studies) | Switch between rules or tasks | Impaired (g = −0.300), from few studies |
| Cognitive inhibition (selective attention) | Ignore distracting information, as in flanker tasks | Impaired (g = −0.208) |
| Response inhibition | Stop an action, as in stop-signal and go/no-go tasks | Improved (g = +0.296) |
Effect sizes here are in a standard unit, g; a minus sign means stressed participants did worse. The working-memory effect was larger when the task placed a high load on working memory (g = −0.303) than when it did not (g = −0.049), and it became more impairing as the gap between the start of the stressor and the task grew [4]. The authors read the overall pattern as a state of more reactive processing of salient stimuli, but greater control over actions [4].
In practice, that fits a familiar experience: under pressure, holding several things in mind at once and ignoring distractions get harder, even though you may still be able to stop yourself from doing something.
How stress affects memory: learning, storing and recalling
Memory has phases, and stress affects them differently. A 2017 meta-analysis pooled 113 studies with 6,216 participants and sorted them by when the stress happened [2].
| When stress happened | What it did to memory |
|---|---|
| Before or during learning (encoding) | No overall effect on average. Stress that began about 22 minutes or more before learning impaired memory, while material directly related to the stressor tended to be remembered better |
| Soon after learning (storing, or consolidation) | Improved later memory on average (g = +0.206). The benefit appeared when the stress happened in the same setting as the learning; in a different setting there was no significant effect |
| Just before or during a memory test (retrieval) | Impaired recall (g = −0.215), more for emotional material than for neutral material |
These summaries come from the meta-analysis [2]. Two points stand out. First, stress can help memory as well as hurt it, depending on timing and on whether the material is connected to the stressful event. Second, although stress reliably raised cortisol, the size of the cortisol rise did not predict the size of the memory effect [2], so stress hormones are not the whole story.
The retrieval finding is the one most people recognise: a name or a fact you know well may not come to you during a tense exam or a job interview.
Why it happens: the mechanisms (background)
Research on the brain's stress systems, much of it in animals, suggests why these effects happen. It describes how stress might change thinking; it is not evidence that any technique fixes it.
One review describes the prefrontal cortex, which supports our highest-order thinking abilities such as working memory, as the brain region most sensitive to the harmful effects of stress [5]. In this account, even quite mild uncontrollable stress can cause a rapid loss of prefrontal abilities, partly because the stress-related brain chemicals noradrenaline and dopamine each have an inverted-U-shaped influence on working memory: too little or too much impairs it [5]. The same review summarises human studies in which people who felt in control of a stressful situation were often not impaired [5].
Is some stress good for you? The inverted U and its limits
You may have seen a curve showing that performance rises with stress or arousal up to an ideal point and then falls. It is usually credited to Robert Yerkes and John Dodson.
Their 1908 study did something more specific. Dancing mice learned to choose a white box over a black one, and received an electric shock when they chose wrongly; the experimenters varied both the strength of the shock and how hard the two boxes were to tell apart [6]. When the discrimination was difficult, the mice learned fastest with a weak shock close to the threshold, while easier discriminations could be learned well under strong shocks [6].
A review of the law's history found that later researchers and textbook authors turned this into a statement about the effects of punishment, motivation, arousal, anxiety, tension or stress on learning, performance or memory, and often attributed these changes to Yerkes and Dodson themselves [7]. A critical review of its use in management writing concluded that, as a law of work stress, it has no basis in empirical fact, and that managers should not try to raise performance by raising employees' stress [8].
The research above suggests a more modest picture. A narrower inverted-U effect of specific brain chemicals on working memory is described in the mechanism research [5]. Stress shortly after learning, in the same setting, improved later memory, and stress-related material was sometimes remembered better [2]. Neither finding gives you an ideal stress level to aim for, and neither makes stress during a test helpful.
Exams: what you can do beforehand
If stress makes recall harder at the moment of the test, how well you learned the material may matter. In a single experiment, 120 participants learned 30 words and 30 pictures, either by restudying them or by practising recall [9]. A day later, half of them gave an unprepared speech and solved maths problems in front of judges and peers [9]. In a test 5 minutes into the stress task, stress made no difference. In a second test about 25 minutes after the stress began, stressed participants who had restudied recalled fewer items than unstressed ones, while stressed participants who had practised recall were not impaired [9].
A commentary on the study pointed out its limits: the recall-practice group remembered more overall, so the protection may simply reflect stronger learning; cortisol was not measured; and the material was simple, so the finding needs testing with more complex material [10]. Practising recall is worth doing anyway: LaserMind grades active recall E1 (strong evidence) for long-term retention of studied material. Whether it also protects memory against exam stress is not established.
What helps in the moment
Brief breathing and relaxation exercises are a reasonable way to settle before a stressful task. The evidence behind them is about how stressed or relaxed people feel, not about memory or attention.
Slow breathing. A meta-analysis of 12 randomised trials with 785 adults found that breathwork, deliberate breathing techniques of several kinds, was linked with lower self-reported stress than control conditions, a small-to-medium effect; most trials were at moderate risk of bias, and the authors urged caution [11]. A systematic review of 15 studies of slow breathing, under ten breaths a minute, in healthy people found it linked with more comfort and relaxation, less arousal and anxiety, and higher heart-rate variability [12]. LaserMind grades slow breathing E2 (conditional evidence) for short-term stress regulation. The Breath Counter's "Breathing circle 4s/6s" option shows a circle that grows as you breathe in for about 4 seconds and shrinks as you breathe out for about 6; never hold your breath, and stop if you feel dizzy.
Progressive muscle relaxation. A systematic review of 46 studies with more than 3,400 adults concluded that progressive muscle relaxation reduced self-reported stress, anxiety and depression, and worked better combined with other techniques [13]. In a randomised trial with 60 healthy undergraduates, one 20-minute recorded session raised self-reported relaxation compared with a control group, as did deep breathing and guided imagery [14]. The Guided Sessions tool includes a 10-minute progressive muscle relaxation session, read aloud by your browser's own voice with quiet pauses: you gently tense one muscle group for about five seconds, then release it, never to the point of pain. You can stop at any time.
Two notes of caution. In the 60-student trial, deep breathing first raised physiological arousal, which then quickly returned to its starting level [14]. And none of these studies tested whether the exercises restore working memory or recall under stress.
Sleep matters too. Sleep and memory covers what sleep loss does to attention and to learning.
When to talk to a doctor
Stress before an exam or a big meeting is normal. Talk to a doctor or another qualified professional if:
- stress, worry or low mood lasts for weeks, or keeps coming back;
- it affects your studies, work, relationships or sleep;
- you have panic attacks, or physical symptoms that worry you;
- memory or concentration problems are new, getting worse, or affecting daily life;
- you are using alcohol or other substances to cope.
If you ever think about harming yourself, contact your local emergency number or a crisis line straight away. This article is general science education, not medical advice, and LaserMind's exercises and tools are practice, not a test or a treatment for any condition.
What the research says
Try it on LaserMind
▶ Breath Counter & PacerTurn on "Breathing circle 4s/6s" and follow it for a few minutes before a stressful task.
Try it on LaserMind
▶ Guided Sessions (audio)Try the 10-minute progressive muscle relaxation session, and stop whenever you like.
What research has not established
- Most studies used brief laboratory stressors, such as a speech in front of judges or a hand in ice-cold water, with young, healthy adults, mostly from Western countries [4]. Results may differ for older adults, for children, and for real exams or workplaces.
- Some effects rest on few studies: cognitive flexibility on six [4]. The memory meta-analysis found signs of publication bias for stress before learning and before testing [2].
- Effect sizes are averages across tasks and stressors. They do not predict how stress will affect a particular person on a particular day.
- Research on chronic stress, lasting months or years, draws on animal and human studies, and the mechanisms described here are models, not tested explanations of any one person's memory [3][5].
- The breathing and relaxation studies measured how stressed or relaxed people said they felt. LaserMind's Breath Counter and Guided Sessions have not been tested in trials of their own.
Frequently asked questions
Why do I go blank in exams when I knew the answer? Stress just before or during a memory test impaired recall in the meta-analysis, especially for emotional material [2]. Going blank under pressure does not mean you never learned the material.
Does cramming under pressure help me remember? The evidence does not support it. Stress that began about 20 minutes or more before learning impaired memory for the material [2]. Planning study over several days, and testing yourself as you go, is a better bet.
Can stress cause lasting memory problems? Research on long-term stress, in animals and in people, points to effects on brain structures involved in cognition [3]. It cannot tell you what is happening in your case. If memory problems are new, getting worse or affecting daily life, talk to a doctor.
What the research says
Last evidence check 2026-10-17A meta-analysis of 12 randomised trials with 785 adults found breathwork was linked to lower self-reported stress than control conditions (a small-to-medium effect); most trials had a moderate risk of bias and the authors urge caution. Health [11]
A systematic review of 15 studies found slow breathing was linked with more comfort and relaxation and less arousal and anxiety in healthy people, alongside higher heart-rate variability. Health [12]
A systematic review of 46 studies in more than 3,400 adults concluded that progressive muscle relaxation reduced self-reported stress, anxiety and depression scores, and worked better combined with other techniques than on its own. Health [13]
In a randomised trial with 60 healthy undergraduates, one 20-minute recorded session of progressive muscle relaxation raised self-reported relaxation compared with a control group, as did deep breathing and guided imagery. Trained task [14]
References
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- Lupien, S. J., McEwen, B. S., Gunnar, M. R., & Heim, C. (2009). Effects of stress throughout the lifespan on the brain, behaviour and cognition. Nature Reviews Neuroscience, 10(6), 434–445. https://doi.org/10.1038/nrn2639
- Shields, G. S., Sazma, M. A., & Yonelinas, A. P. (2016). The effects of acute stress on core executive functions: A meta-analysis and comparison with cortisol. Neuroscience & Biobehavioral Reviews, 68, 651–668. https://doi.org/10.1016/j.neubiorev.2016.06.038
- Arnsten, A. F. T. (2009). Stress signalling pathways that impair prefrontal cortex structure and function. Nature Reviews Neuroscience, 10(6), 410–422. https://doi.org/10.1038/nrn2648
- Yerkes, R. M., & Dodson, J. D. (1908). The relation of strength of stimulus to rapidity of habit‐formation. Journal of Comparative Neurology and Psychology, 18(5), 459–482. https://doi.org/10.1002/cne.920180503
- Teigen, K. H. (1994). Yerkes-Dodson: A Law for all Seasons. Theory & Psychology, 4(4), 525–547. https://doi.org/10.1177/0959354394044004
- Corbett, M. (2015). From law to folklore: work stress and the Yerkes-Dodson Law. Journal of Managerial Psychology, 30(6), 741–752. https://doi.org/10.1108/JMP-03-2013-0085
- Smith, A. M., Floerke, V. A., & Thomas, A. K. (2016). Retrieval practice protects memory against acute stress. Science, 354(6315), 1046–1048. https://doi.org/10.1126/science.aah5067
- Wolf, O. T., & Kluge, A. (2017). Commentary: Retrieval practice protects memory against acute stress. Frontiers in Behavioral Neuroscience, 11. https://doi.org/10.3389/fnbeh.2017.00048
- Fincham, G. W., Strauss, C., Montero-Marin, J., & Cavanagh, K. (2023). Effect of breathwork on stress and mental health: A meta-analysis of randomised-controlled trials. Scientific Reports, 13, 432. https://doi.org/10.1038/s41598-022-27247-y
- Zaccaro, A., Piarulli, A., Laurino, M., Garbella, E., Menicucci, D., Neri, B., & Gemignani, A. (2018). How breath-control can change your life: A systematic review on psycho-physiological correlates of slow breathing. Frontiers in Human Neuroscience, 12, 353. https://doi.org/10.3389/fnhum.2018.00353
- Muhammad Khir, S., Wan Mohd Yunus, W. M. A., Mahmud, N., et al. (2024). Efficacy of progressive muscle relaxation in adults for stress, anxiety, and depression: A systematic review. Psychology Research and Behavior Management, 17, 345–365. https://doi.org/10.2147/prbm.s437277
- Toussaint, L., Nguyen, Q. A., Roettger, C., Dixon, K., Offenbächer, M., Kohls, N., Hirsch, J., & Sirois, F. (2021). Effectiveness of progressive muscle relaxation, deep breathing, and guided imagery in promoting psychological and physiological states of relaxation. Evidence-Based Complementary and Alternative Medicine, 2021, 5924040. https://doi.org/10.1155/2021/5924040