Differences between Mondays and other days of the week in hair cortisol across the distribution of cortisol (a), at the 90th quantile of cortisol (b), and at the 90th quantile of total glucocorticoid production (c)
A research study led by Professor Tarani Chandola from the Department of Sociology, Faculty of Social Sciences at the University of Hong Kong (HKU) has revealed that Mondays uniquely drive long-term biological stress, regardless of working status, with implications for heart health.
The research has identified a striking biological phenomenon: older adults who feel anxious on Mondays exhibit significantly higher long-term stress hormone levels, up to two months later. This "Anxious Monday" effect, observed in both working and retirees, points to a deep-rooted link between the start of the week and dysregulation of the body's stress response system, a known driver of cardiovascular disease (CVD). Published in the Journal of Affective Disorders, the study analysed data from over 3,500 older adults participating in the English Longitudinal Study of Ageing (ELSA).
Key Findings
- 23% Higher Cortisol Levels: Older adults reporting Monday anxiety had 23% elevated cortisol levels in hair samples (reflecting cumulative exposure over two months) compared to peers anxious on other days.
- Non-Workers Not Spared: The effect persisted among retirees, challenging assumptions that workplace stress alone explains Monday's toll.
- CVD Connection: Mondays are linked to a 19% spike in heart attacks—this study identifies HPA-axis dysregulation as a potential biological bridge.
- Not just higher levels of Monday anxiety: Only 25% of the Monday effect was due to greater feelings of anxiety on Mondays. The rest was because of the greater effect of feeling anxious on Mondays compared to other days.
The hypothalamic-pituitary-adrenal (HPA) axis regulates stress hormones like cortisol, which, when chronically elevated, contribute to hypertension, insulin resistance, and immune dysfunction. While prior research noted higher cortisol on weekdays versus weekends, this is the first study to pinpoint Mondays as uniquely disruptive. The findings suggest societal rhythms—not just job demands—embed themselves in human physiology, with lasting health risks.
"Mondays act as a cultural 'stress amplifier,'" said Professor Chandola. "For some older adults, the week's transition triggers a biological cascade that lingers for months. This isn't about work—it's about how deeply ingrained Mondays are in our stress physiology, even after careers end.
The study underscores how the "Monday blues" can become biologically embedded, with chronic stress hormone dysregulation posing long-term cardiovascular risks. Addressing Monday-specific stress could unlock new strategies to combat heart disease in aging populations.
The full paper can be accessed at: https://authors.elsevier.com/sd/article/S0165-0327(25)01053-5
