When stress becomes a permanent feature, many people feel like they no longer have the same character: less patience, less desire to see people, more spikes that go away on their own. For a long time, psychologists thought that the adult personality remained relatively stable, even under pressure. However, a large international study shows that chronic stress can, little by little, modify certain traits.
This research was conducted by psychologist William J. Chopik at Michigan State University and published in 2025 in the journal
Psychology and Aging. The team followed 2022 adults for almost 20 years and linked their reactivity to daily stress to the evolution of their big five personality traits. When emotional sensitivity to stress increased over the years, extraversion, openness to experience and agreeableness declined significantly. In other words, everyday life ends up silently writing part of our character.
Chronic stress: a personality that gradually closes down
In everyday life, this shift resembles something very banal: we feel more irritable, more nervous, easily overwhelmed, we avoid outings or new things that previously required a little effort but provided pleasure. In terms of traits, this corresponds to a decrease in extroversion (less sociable), openness (less curious) and agreeableness (less accommodating and warm).
In William J. Chopik’s study, participants regularly described how stressful their day had been and how upset, tense, or overwhelmed they felt. At regular intervals, they also completed personality questionnaires. People whose emotional reactivity to stress increased became, on average, more reserved and less focused on others, while those who remained relatively calm showed almost no change. Neuroticism, that is, basic emotional instability, didn’t really move, indicating that the effect is more than just being “anxious in nature.”
What stress does to the brain and the way we see the world
Behind these changes lies the biological stress system, the hypothalamic pituitary adrenal axis, which controls the secretion of cortisol. When this axis is activated too often, the brain remains in maximum alertness, to the detriment of memory, concentration and energy. We spot threats more, we ruminate more, we have fewer resources to listen, to joke, to open up to something new.
Longitudinal work suggests that these repeated micro-experiences eventually become embedded in personality. This is striking, because normally, as adults get older, they tend to become a little more agreeable and more emotionally stable. A very stressful environment can change this trajectory: instead of gaining flexibility and tolerance, a person becomes rigid and withdraws, which further fuels their feeling of no longer being themselves.
Protect your character by working on your reactivity to stress
William J. Chopik’s study describes strong links but does not prove a single cause: stress can change personality, and a personality that withdraws may also handle stress less well. This loop is not fixed, however, because the way of reacting to stress needs to be worked on. Research cited by the team shows that mindfulness, regular life routines and quality social support reduce sensitivity to everyday stressors.
Taking care of your psychological resilience therefore amounts to protecting your future self. A simple exercise consists of remembering a calmer period of your life and describing how we behaved then with others, what attracted us, what amused us. If the gap with today is massive, lasting and causes suffering to those around you, asking for help from a health professional can help you find a style of functioning that more closely resembles your base, even in an imperfect environment.