How Chronic Stress Shows Up in Children's Bodies

Introduction

When a child lives with a chronic physical illness, stress becomes part of their everyday life. The influx of doctor visits, medications, ongoing symptoms, and feelings of exclusion from peers can contribute to declines in mental health. Reports of declining mental health among children are not new, but the reasons behind this decline remain unclear. A recent Canadian study offers an important suggestion: long-term stress leaves a biological fingerprint, and that fingerprint may help explain which children are most at risk for mental health struggles.

Stress Response

Many stress studies have established that the physiological response to acute stress involves activation of the endocrine stress-response system, most notably the hypothalamic–pituitary–adrenal (HPA) axis. In children living with long-term physical illness, the HPA axis may remain activated for prolonged periods, leading to sustained cortisol release. Over time, elevated cortisol levels can affect mood, behavior, and emotional regulation.

Most stress studies measure cortisol using saliva or blood samples, which capture stress at a single point in time. This particular study focused on measuring cortisol in hair. Because hair grows approximately one centimeter per month on average, a small hair sample can reflect average stress levels over the past few months, making it a useful tool for studying chronic stress.

The Study Model

Researchers followed 244 children aged 2 to 16 who were living with a chronic physical illness. The children’s emotional and behavioral symptoms were reported and tracked for four consecutive years. These symptoms were divided into two categories: internalizing and externalizing. Internalizing symptoms included anxiety and depression, while externalizing symptoms included hyperactivity, impulsivity, and conduct problems.

Results

Consistently High Stress Levels

Most children in the study had cortisol levels that started high and remained consistently elevated. These children experienced higher levels of anxiety, depression, and behavioral problems.

Consistently Low Cortisol Levels

A smaller group of children had consistently low cortisol levels. These children did not show better mental health outcomes than the high-stress group. Researchers suggested this pattern may reflect long-term strain on the stress-response system.

High Stress That Decreased Over Time

Children whose cortisol levels were initially high but decreased over time showed lower levels of anxiety, depression, and behavioral problems. Children whose bodies were able to recover from early stress appeared to have better-reported mental health outcomes.

Why Is This Important?

Persistent biological stress may contribute to emotional and behavioral challenges even when symptoms of the physical illness are well managed. Chronic stress in children with long-term illness is often overlooked, and this study confirms that it is real, biological, and measurable. These findings support the importance of routinely addressing mental health as part of caring for children with chronic illness. Reducing long-term stress and supporting recovery may play a significant role in protecting children’s mental health.

Citations:

Admon, R., Treadway, M. T., Valeri, L., Mehta, M., Douglas, S., & Pizzagalli, D. A. (2017). Distinct trajectories of cortisol response to prolonged acute stress are linked to affective responses and hippocampal gray matter volume in healthy females. Journal of Neuroscience, 37(33), 7994–8002. https://doi.org/10.1523/JNEUROSCI.1175-17.2017

Littler, Emma A. L., Zahid A. Butt, Andrea Gonzalez, and Mark A. Ferro. 2025. “Association Between Hair Cortisol and Psychopathology in Children With a Chronic Physical Illness.” Stress and Health: e70087. https://doi.org/10.1002/smi.70087.

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