Hi A good tool to measure stress is to measure heart rate variability or skin conductance. Those parameters as indicator of the autonomous system would help you for an objective definition of the stress/ mental state.
Yes, by testing autonomic functions , changes in heart rate variability and 24hr Blood Pressure monitoring would give an objective evaluation of stress although quantificatiom is not possible owing to its multifactorial aetiology.
I Think the best combination would be autonomic functions including heart rate variability along with the changes in salivary cortisol ( after ruling out other causes for its increment). Than the multi factorial etiology of HRV can also be eliminated to a great extent. Because stress leads to hypothalamic–pituitary–adrenal axis (HPA axis) overactivity and through this it causes activation of both autonomic system as well as adrenal hyper-secretion of cortisol.
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