Stress and the hormone cortisol: ten signs not to underestimate

Initial note: This article was previously published and updated according to scientific and informative criteria. The information is for informational purposes only and does not replace medical advice. If you suspect a health problem, consult a healthcare professional.

In brief

• Cortisol is the main hormone in the stress response; it has adaptive functions but can become harmful if exposure is repeated or prolonged.
• High or misaligned cortisol levels can be associated with sleep disturbances, appetite changes, metabolic alterations, skin changes, and gastrointestinal symptoms.
• Many indicators associated with stress come from observational studies; the causal relationship depends on the context, duration, and extent of exposure.
• Lifestyle interventions (sleep, physical activity, relaxation techniques, balanced diet) are plausible for reducing the impact of stress, but do not replace medical consultations.

Abstract: what does science say?

Cortisol is a glucocorticoid produced by the adrenal cortex that participates in the regulation of energy metabolism, inflammatory balance, and the adaptive response to acute stimuli. Under normal conditions, it shows a marked diurnal variation (morning peak, nocturnal minimum) that coordinates wakefulness, metabolism, and immunity. The literature indicates that repeated stress or chronic exposure to high or misaligned cortisol levels are associated with a series of clinical signs — insomnia, fatigue, central adiposity gain, altered immune response, gastrointestinal disturbances, appetite changes, skin alterations, and mood changes. Much data comes from observational studies, experimental evidence on sleep deprivation, and Mendelian randomization genetic studies that clarify some directions of association. However, interpretation requires caution: altered values can be a cause, effect, or marker of complex conditions, and the clinical impact depends on magnitude, duration, genetic interactions, and environmental factors.

Main section

What is cortisol and why is it important

Cortisol is the main output of the hypothalamic-pituitary-adrenal (HPA) axis. In response to a stressful event, the HPA axis is activated, increasing cortisol production, which promotes energy availability, modulating glucose, blood pressure, and inflammatory reactions. This is an adaptive response to acute threats, but when activation becomes prolonged or the daily dynamic flattens, the initial benefits can turn into risk factors for metabolic and cardiovascular health. Synthetic reviews on the stress system and the consequences of its dysregulation provide a consolidated framework of potential clinical and biological repercussions. [1]

The ten signs not to underestimate

Below are common signs associated with a state of chronic stress or cortisol dysregulation. For each point, a distinction is made between observational association, biological plausibility, and degree of evidence.

1) Pain sensitivity and musculoskeletal pain

The relationship between chronic stress and pain is complex: repeated activation of stress systems can alter central pain control and promote sensitization of nociceptive pathways. In some clinical pictures, altered adrenocortical response patterns (hypo- or hyperfunction) associated with persistent pain are observed, suggesting that stress may contribute to pain chronicity through endocrine, inflammatory, and neuroplastic pathways. The nature of the relationship varies between types of pain and populations and remains partly equivocal. [2]

2) Sleep disturbances (difficulty falling asleep or staying asleep)

Cortisol follows a circadian rhythm: a morning peak and an evening reduction promote sleep. Acute or chronic stress can "flatten" this curve or raise evening levels, resulting in difficulty initiating or maintaining sleep. Experimental studies on sleep restriction show increases in evening cortisol and alterations in the amplitude of the diurnal decline, confirming the bidirectionality of sleep–cortisol. [3][4]

3) Persistent fatigue (chronic tiredness)

Those who report persistent fatigue may show alterations in the dynamics of the HPA axis; in some cases, abnormal cortisol levels or an attenuated stress response are observed. The literature indicates associations between altered secretion profiles and the sensation of chronic fatigue, but the causal relationship is often modulated by comorbidities, sleep disturbances, and psychological factors. Therefore, cortisol can be a useful marker, but not diagnostic on its own. [4]

4) Weight gain, especially central

High or prolonged levels of glucocorticoids favor adipose tissue remodeling, with an increase in visceral fat in clinical hypercortisolism syndromes (e.g., Cushing's). Genetic and Mendelian randomization studies have explored the direction of the relationship between cortisol and obesity: the results show a complex and bidirectional relationship, with evidence that obesity can also influence cortisol levels and vice versa. [5][6]

5) Increased susceptibility to infections and slower recovery

Glucocorticoids modulate inflammation and immune function: high or prolonged exposures can suppress some immune defenses and alter the inflammatory response. This mechanism is the basis of the therapeutic use of corticosteroids and explains why chronic exposure can increase vulnerability to infections. [7]

6) Persistent craving for high-energy foods (sugars and fats)

Stress influences reward circuits and metabolic hormones (e.g., insulin, ghrelin, leptin), promoting preferences for high-calorie foods. Reviews and meta-analyses indicate that stress and cortisol can promote the intake of "comfort food," contributing to changes in weight and body composition in certain individuals. The relationship is moderated by sex, environment, and behavioral history. [8]

7) Reduced sexual desire

Chronic stress activation influences the balance between reproductive hormones and stress hormones: prolonged cortisol levels can interfere with reproductive axes and with psychological factors that regulate libido. The effect is mediated by the set of endocrine, psychosocial, and metabolic interactions; the presence of the symptom warrants in-depth clinical evaluation. [1]

8) Gastrointestinal disturbances (nausea, cramps, diarrhea or constipation)

The gastrointestinal tract is sensitive to stress mediators: cortisol and related peptides modulate motility, secretions, intestinal permeability, and gut microbiota composition. These interactions explain why chronic stress can worsen functional gastrointestinal symptoms (e.g., irritable bowel syndrome) and alter nutrient absorption. The literature on the microbiota–gut–brain axis supports biological plausibility and observational associations. [11]

9) Anxiety, nervousness, and mood changes

Cortisol and other neuroendocrine mediators interact with brain circuits that regulate emotions and motivation. Alterations in cortisol rhythms have been observed in various mood and anxiety disorders, but the patterns are not unequivocal: some conditions show hypercortisolemia, others hypocortisolemia or flattened diurnal curves. Evidence indicates that the relationship is complex and subject to multiple confounding factors. [1][4]

10) Skin changes and signs of skin aging

Exposure to glucocorticoids (endogenous or exogenous) can reduce fibroblast proliferation and collagen production, promoting skin atrophy, fragility, and slowed repair. Experimental and observational studies support the biological plausibility that excessive local glucocorticoid activity contributes to signs of skin aging. Studies on enzymes that regulate tissue cortisol (e.g., 11β-HSD1) show effects on dermal structure in aging. [10]

What it means in practice

For the general public: recognizing signs of prolonged stress allows one to seek a medical or public health evaluation before tangible complications appear. No single symptom is diagnostic of "excess cortisol"; many signs are common and multifactorial. Evidence suggests that lifestyle interventions (regular sleep, adequate physical activity, balanced diet, caffeine intake control, stress reduction techniques such as meditation or relaxation exercises) have plausible and often demonstrated effects in improving sleep-wake rhythm balance and reducing some subjective signs of stress. Some herbs (e.g., Ashwagandha) have been studied in RCTs and meta-analyses to reduce cortisol levels and perceived stress; the data are promising but not exhaustive, and use should consider product quality, interactions, and clinical advice. [9][15]

Key points to remember

• Cortisol is essential for the stress response, but its prolonged or misaligned exposure can promote metabolic and psychological risks.
• Many common signs (insomnia, fatigue, abdominal weight gain, gastrointestinal problems) can correlate with stress dysregulation but are not unequivocal proof.
• Evidence ranges from experimental studies to observational studies and genetic analyses: interpretations require caution.
• Lifestyle approaches are the first practical line for the general population; therapies or supplements should be discussed with a doctor.

Limitations of evidence

It is important to distinguish between different levels of evidence. Many studies are observational: they show associations but do not establish direct causality. Experimental studies (for example, sleep deprivation) demonstrate that manipulating sleep alters the cortisol profile, providing mechanistic evidence; however, these experiments may be short-term and conducted on selected samples. Genetic analyses such as Mendelian randomization help infer directions of association on a large scale, but depend on the validity of genetic instruments and do not completely eliminate the complexity of environmental interactions. Finally, measuring cortisol is complex: total, free, salivary, or hair plasma concentrations reflect different aspects of exposure and have methodological limitations that influence interpretation. [2][3][4][5][6]

Editorial conclusion

Cortisol is a central marker of the stress response and provides a bridge between psychosocial events and biological responses. Signs such as insomnia, persistent fatigue, changes in appetite, increased abdominal fat, gastrointestinal disturbances, skin alterations, and mood changes warrant integrated clinical attention. Modern science offers tools (experimental studies, reviews, genetic analyses) that improve understanding, but individuals remain subject to multiple determinants. For this reason, lifestyle interventions remain the first practical and safe approach; any therapeutic or integrative choice should be evaluated with a healthcare professional, considering risks, benefits, and available evidence.

Editorial note

This text is updated using peer-reviewed scientific sources and transparency criteria. The information is for informational purposes only and does not replace a medical visit. Bibliographic references are provided for verifiability and further study.

SCIENTIFIC RESEARCH

1. Russell, G.M., et al. The human stress response. Nature Reviews Endocrinology. 2019. https://doi.org/10.1038/s41574-019-0228-0.
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3. Guyon A, et al. Adverse effects of two nights of sleep restriction on the hypothalamic-pituitary-adrenal axis in healthy men. J Clin Endocrinol Metab. 2014;99(8):2861-2868. https://doi.org/10.1210/jc.2013-4254.
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8. McEwen BS. Stress, allostasis, and the clinical implications. Biological Psychiatry. 2013. (review on stress and eating behaviors). https://doi.org/10.1016/j.biopsych.2013.01.032.
9. Chandrasekhar K, Kapoor J, Anishetty S. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high‑concentration full‑spectrum extract of Ashwagandha root in reducing stress and anxiety in adults. Indian J Psychiatry. 2012;34(3):255–262. https://doi.org/10.4103/0253-7176.106022.
10. Tiganescu A, et al. 11β-Hydroxysteroid dehydrogenase blockade prevents age‑induced skin structure and function defects. J Clin Invest. 2013;123(7):3051–3060. https://doi.org/10.1172/JCI64162.
11. Foster JA, McVey Neufeld KA. Stress and the microbiota–gut–brain axis: regulation by the microbiome. Neurobiology of Stress. 2017; Synthesis publication. https://doi.org/10.1016/j.ynstr.2017.03.001.