The main means of measuring stress are the following:

Stress-measurement questionnaires (Daily Stress Scale, Perceived Stress Scale etc.)

Interviews (Life Events and Difficulties Schedule, Standardized Event Rating System)

Biomarkers of stress measurement: salivary or hair cortisol, CRH, ACTH, AVP, DHEA, catecholamines (epinephrine norepinephrine and dopamine).