Although psychological approach in measuring stressors provides to some extent the mechanisms in which stress affects health or illness, a better measure would be a physical or biological measure. Psychological measures such as questionnaires are not very reliable as the individuals interviewed may not report the stressors due to a number of reasons, such as adaptability and self consciousness. (Amsterdam et al 2000).

A physical stress measure on the other hand is more feasible as its focus is on the autonomic nervous system. Measurement of heart rate variability and blood pressure readings has been used as markers of the sympathetic activity. Other new informative diagnostic characteristics of human functional states that are highly efficient and sensitive in revealing the early signs of emotional stress and stress induced disturbances include respiration rate, vital lung capacity, and forced vital capacity (Sudakov & Glazachev, 2001). An ideal biological stress marker would have a long half life and have a well-defined population distribution or not be affected greatly by age or sex (Kelly & Hertznam, 2001). Stress hormones such as cortisol, dehydroepiandrosterone (DHEA) and prolactin are also important identification markers in indicating a stressful situation.

Cortisol has catabolic function and is significantly and positively related to stress effects. Cortisol made in the zona fasciculata of the adrenal cortex, is the predominant glucocorticoid in humans constituting 80% of the 17-hydroxycorticoids in plasma. Cortisol release occurs with a periodicity that is regulated by the diurnal rhythm of ACTH release. Consequently, cortisol levels are highest in the morning, shortly after awakening, and lowest in the late afternoon and early evening (Rosmond & Dallman 1998). The production of cortisol is also regulated by a negative feedback loop consisting of CRH (hypothalamus) and ACTH (anterior pituitary)

In contrast, dehydroepiandrosterone (DHEA) also made by the fasciculata and reticularis of the adrenal cortex and stimulated by ACTH (Moriyama et al 2000) has antistress activity and has a significant positive relationship with the affective state of decrease in anxiety and stress effects (Goodyear et al 2000). The sulfate conjugate, DHEA-S is frequently measured as the levels of DHEA-S is the highest compared to all other steroidal hormones and 100 times more than DHEA (Guazzo et al 1996). It also not influenced by diurnal or daily changes.

Prolactin (PRL), also prone to changes under a stressful condition (Peterson 1997) is secreted by endophilic cells in the anterior pituitary called lactotropes. Prolactin together with growth hormone (GH) is classified as the growth-hormone-prolactin-chorionic somatomammotropin group.

References

Amsterdam JGC, Opperhuizen A, Olff, M. 2000. Stress Markers of Health Status. Research for man and environment, 3-25

Sudakov KV, Glazachev OS. 2001. Multiple physiological assessments of long term stress at work and in daily life:a system approach. In Theorell T (ed.): Everyday Biological Stress Mechanisms. Adv Psychosom Med. Basel, Karger, 22:61-79

Kelly SJ, Hertzman C. 2001. Finding a stress measure in the literature and taking it into the field. In Theorell T (ed.): Everyday Biological Stress Mechanisms.Adv Psychosom Med. Basel, Karger, 22:61-79

Rosmond R, Dallman MF. 1998. Stress-related cortisol secretion in men: Relationships with abdominal obesity and endocrine, metabolic and hemodynamic abnormalities. J Clin. Endo & Metabolism, 83(6):1853-1859

Moriyama Y, Yasue H, Yoshimura M, Mizuno Y, Nishiyama K, Tsunoda R, Kawana H, Kugiyama K, Ogawa H, Saito Y, Nakao K. 2000. The plasma levels of dehydroepiandrosterone sulfate are decreased in patients with chronic heart failure in proportion to the severity. J Clin. Endo & Metabolism, 85(5): 1834-1840

Goodyer IM, Herbert J, Tamplin A., Altham PME. 2000. Recent live events, cortisol, dehydroepiandrosterone and the onset of major depression in high-risk adolescents. Br. J. Psychiatry, 177: 499-504

Guazzo EP, Kirkpatrick PJ, Goodyer IM, Shiers HM, Herbert J. 1996. Cortisol, dehydroepiandrosterone (DHEA), and DHEA sulfate in the cerebrospinal fluid of man: relation to blood levels and the effects of age. J. Clin. Endo. Metabolism, 81:3951-3960

Peterson CM. 1997. Prolactin: Physiologic and pathologic associations. Human Reproduction: Clinical, Pathologic and Pharmacological correlations