Background: Stress, as a psychophysiological response, arises when individuals encounter challenging or adverse situations. Extensive research over the past decades has demonstrated stress's profound effects on both the nervous system and overall health, showing associations with memory impairments, cognitive decline, and physiological damage in chronic cases. Stress-induced biochemical changes impact critical systems, including the hypothalamic-pituitary-adrenal (HPA) axis, autonomic nervous system (ANS), and immune responses. These physiological responses influence various biomarkers and immune functions, increasing vulnerability to chronic diseases.

Aim: This review aims to update and synthesize findings on the biochemical biomarkers involved in stress responses, particularly the role of cortisol and related biochemical indicators in both acute and chronic stress conditions.

Methods: A comprehensive review of peer-reviewed literature was conducted, focusing on studies investigating stress biomarkers. Data were sourced from multiple databases, covering research on cortisol measurements in hair, saliva, blood, and other biological samples, and studies exploring the physiological responses regulated by the HPA axis, ANS, and immune system.

Results: Findings highlight cortisol as a significant biomarker in stress, with measurement methods, including hair and salivary cortisol, offering reliable indicators for chronic stress levels. Chronic stress influences hormone levels, such as those produced by the HPA axis, and leads to increased pro-inflammatory cytokines like IL-6, TNF-alpha, and C-reactive protein. Additionally, elevated oxidative stress markers, such as glutathione peroxidase and superoxide dismutase, reveal the body's antioxidant response under stress. Studies also link stress responses to various long-term health outcomes, including metabolic disturbances, immunosuppression, and age-related physiological changes.

Conclusion: This review underscores the biochemical changes triggered by stress and emphasizes cortisol as a key chronic stress biomarker. The cumulative evidence suggests that biochemical monitoring of stress can aid in early identification of stress-induced health risks. Future research should focus on refining stress measurement techniques and exploring interventions that target these physiological markers to improve health outcomes.