In reviews of Robert M. Sapolsky’s book, Why Zebras Don’t Get Ulcers (1), readers love the central premise—that animals like zebras only activate their “fight-or-flight” response for short-term physical crises (like escaping a predator), whereas humans turn on that same powerful system continuously over abstract, long-term worries (like work or money).
It goes on to say that the body does not respond to “change” itself—it responds to how the brain interprets change (2,3). When a change is perceived as uncertain, uncontrollable or threatening, the brain activates the stress response (the sympathetic nervous system and Hypothalamic-Pituitary-Adrenal axis), releasing adrenaline and cortisol to help us cope (4,5). When that response is prolonged, it can begin to affect sleep, mood, immunity, metabolism and cardiovascular health (4,6,7).
Sapolsky also emphasises that, unlike zebras (which experience short-lived physical threats), humans can activate the same physiological stress response simply by anticipating future events, worrying about uncertainty or repeatedly thinking about change (1). In other words, it is often our perception and anticipation of change, rather than the change itself, that drives the body’s stress response (2,3).
The funny thing is, your brain can’t always tell the difference between running away from a lion… and pressing “Send” on an important email. This is because, for humans, change and stress can become very closely interlinked. There is robust evidence for several interconnected physiological processes:
- The brain initially interprets uncertainty as a potential threat. Even positive changes (a promotion, moving house, becoming a grandmother) activate brain regions involved in detecting uncertainty and maintaining safety (3).
- The autonomic nervous system responds. The sympathetic (“fight, flight or freeze”) system becomes more active, increasing heart rate, blood pressure, muscle tension and alertness (4,5).
- The HPA (hypothalamic-pituitary-adrenal) axis is activated, increasing cortisol production (4,5).
- Sleep is often disrupted. When cortisol levels stay high, your body remains in a more alert, “ready for action” state. This can make it harder to fall asleep, cause you to wake more often during the night, and reduce the amount of deep, restorative sleep your body needs to recover (6). This can occur even when the change is exciting, because the brain continues processing uncertainty (3,6).
- The immune system is affected. Short bursts of cortisol help regulate the immune system, but when cortisol remains high for long periods, it can weaken immune function by reducing the activity of certain immune cells (7). This can make it harder for your body to fight infections and may slow healing (7).
- Energy is diverted. The body prioritises survival over growth, repair, digestion and reproduction, which explains why people often feel tired, develop digestive symptoms or experience changes in menstrual cycles during prolonged periods of change (1,4).
- The brain gradually adapts. Through neuroplasticity, the brain forms new predictions and routines (5,8). As the new situation becomes familiar, the physiological stress response settles, and the parasympathetic nervous system becomes more active again (4,8).
For women, the physiology is even more relevant because hormonal fluctuations can influence how the body responds to stress and change:
- Oestrogen and progesterone both help regulate the body’s response to stress. Oestrogen supports healthy cortisol regulation and parasympathetic (“rest and digest”) activity, while progesterone has a calming effect on the brain through GABA (gamma-aminobutyric acid), helping to reduce nervous system excitability (9,10).
- As these hormones decline, particularly during perimenopause and menopause, many women become more sensitive to stress, recover more slowly and experience increased sympathetic (“fight or flight”) activity (9-11). Fluctuating hormones can make the physiological response to change feel more intense (10,11).
- Sleep disruption during menopause may further reduce resilience to change (6,11).
- Caring responsibilities, work transitions and ageing often coincide, creating an increased “allostatic load” (the cumulative physiological wear and tear from adapting to repeated stressors) (5,12).
There is additional evidence from stress physiology, neuroscience and psychology to support the theory that change itself is not inherently stressful but for many humans, change and stress often go hand in hand because of how our brain appraises the change:
- Lazarus and Folkman’s Transactional Model of Stress proposed that stress depended on an individual’s appraisal of a situation and their perceived ability to cope, rather than the event itself (2).
- McEwen’s work on allostasis and allostatic load shows that repeated activation of the body’s stress systems in response to ongoing challenges or uncertainty can have cumulative physiological effects (5,12).
- Research in affective neuroscience also shows that uncertainty itself is a potent activator of brain networks involved in vigilance, prediction and threat detection (3).
So, can we break the link between change and stress? This is one of the most interesting areas of modern neuroscience because the goal isn’t to eliminate the stress response—that would be impossible and undesirable. The goal is to help the brain reappraise change as manageable rather than threatening, so the physiological stress response is shorter and less intense (2,3).
The evidence suggests there are several effective approaches:
1. Increase predictability
The brain dislikes uncertainty more than change itself (3). Breaking a large change into small, predictable steps gives the brain evidence that the situation is manageable, reducing activation of the threat response (2,3).
2. Increase your sense of control
One of the strongest predictors of stress is feeling powerless (1,2). Even small choices—deciding when, how or in what order to tackle a change—can reduce physiological stress because they restore a sense of agency (2).
3. Reframe the meaning of the change
According to Lazarus and Folkman’s stress appraisal theory, our interpretation of an event strongly influences our stress response (2). Asking, “What opportunity might this change bring?” or “What strengths can I draw on?” doesn’t deny the difficulty; it helps shift the brain from threat mode towards challenge mode (2).
4. Regulate the nervous system
When the sympathetic (“fight or flight”) response is activated, techniques that stimulate the parasympathetic nervous system can help restore balance (4,8). Evidence shows that practices such as regular physical activity, slow diaphragmatic breathing, mindfulness and meditation, spending time in nature, good-quality sleep and supportive social connection don’t remove the challenge—they help the body recover more quickly from it (13-17).
Physical activity improves resilience by enhancing cardiovascular fitness, regulating stress hormones and increasing parasympathetic activity (13). Slow diaphragmatic breathing, mindfulness and meditation help calm the nervous system, reducing sympathetic (“fight or flight”) activity while promoting a parasympathetic (“rest and digest”) state (14).
Time spent in nature has been shown to lower physiological markers of stress and improve mood (15), while good-quality sleep allows the brain and body to repair, regulate hormones, consolidate memories and support immune function (6).
Supportive social relationships also play a powerful biological role, helping to reduce the body’s stress response through feelings of safety, belonging and connection (16,17). Together, these everyday practices strengthen the body’s ability to adapt to stress and recover more effectively (13).
5. Build familiarity
One reason change becomes less stressful over time is neuroplasticity (8). As the brain repeatedly experiences the new situation without harm, it updates its predictions. What initially felt unfamiliar gradually becomes routine, and the stress response naturally diminishes (8).
6. Support the body’s resilience
During periods of change, the body’s “buffering systems” become especially important. Adequate sleep, balanced nutrition, regular movement and recovery periods all improve resilience, making it easier to adapt without remaining in a prolonged state of physiological stress (5,13).
Once we’ve understood what is happening to our bodies while navigating change and that they are trying to protect us—not sabotage us—we can begin to work with them rather than against them.
A book called The Mountain Is You by Brianna Wiest (18) takes you through some inner work that moves us from understanding why change feels so hard to answering the more emotional question of “How do I grow through it?”. The core message of Wiest’s book is that:
• We often resist change not because we don’t want a better life, but because part of us is trying to protect us from uncertainty, emotional pain or the unfamiliar.
• Many self-sabotaging behaviours are actually protective coping mechanisms that once served a purpose.
• Lasting change comes from developing greater self-awareness, emotional regulation and self-compassion, rather than relying solely on willpower (18).
• Transformation involves gradually replacing old patterns with new ones that align with who we want to become.
Change won’t necessarily stop feeling challenging, but it can stop feeling threatening. The more we support our minds and bodies through periods of uncertainty, the more quickly our nervous system learns that this new chapter is safe—and the less stressful or stress-inducing change becomes.
Modernized References (Vancouver Style)
1. Sapolsky RM. Why Zebras Don’t Get Ulcers: The Acclaimed Guide to Stress, Stress-Related Diseases, and Coping. 3rd ed. New York: Henry Holt and Company; 2004.
2. Biggs A, Brough P, Drummond S. Lazarus and Folkman’s Psychological Stress and Coping Theory. In: Cooper CL, Quick JC, editors. The Handbook of Stress and Health. Chichester: Wiley Blackwell; 2017. p. 351-364.
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5. McEwen BS, Akil H. Revisiting the Stress Concept: Implications for PTSD and Chronic Stress Physiology. Front Neuroendocrinol. 2020;56:100811.
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11. Monteleone P, Mascagni G, Giannini A, Genazzani AR, Simoncini T. Symptoms of menopause—global prevalence, physiology and management. Nat Rev Endocrinol. 2018;14(4):199-215.
12. Guidi J, Lucente M, Sonino N, Fava GA. Allostatic Load and Its Clinical Implications: A Systematic Review. Psychother Psychosom. 2021;90(1):11-27.
13. Silverman MN, Deuster PA. Biological mechanisms underlying the role of physical fitness in health and resilience. Interface Focus. 2014;4(5):20140040.
14. Zou L, Yeung A, Quan X, Boyden JH, Wang H. Mindfulness-based stress reduction and autonomic nervous system regulation: A systematic review. Neural Plast. 2018;2018:1-15.
15. Hunter MR, Gillespie BW, Chen SY. Urban nature experiences reduce stress in the context of daily life based on salivary biomarkers. Front Psychol. 2019;10:722.
16. Eisenberger NI, Cole SW. Social neuroscience and health: neurophysiological mechanisms linking social ties with physical health. Nat Neurosci. 2012;15(5):669-674.
17. Holt-Lunstad J. The Major Health Implications of Social Connection. Curr Dir Psychol Sci. 2021;30(3):251-259.
18.Wiest B. The Mountain Is You: Transforming Self-Sabotage Into Self-Mastery. San Diego (CA): Thought Catalog Books; 2020.