alleryCortisol secretion peaks in the:
AEarly morning (~6-8 AM), follows circadian rhythm
BMidnight
CEvening
DNo variation
Answer & Solution
Correct answer: A. Early morning (~6-8 AM), follows circadian rhythm
**Cortisol diurnal rhythm:** peaks 6-8 AM (preparing body for activity), lowest around midnight.
Controlled by hypothalamic CRH → pituitary ACTH → adrenal cortisol.
Cortisol levels measured at different times diagnostically — disruption indicates Cushing's syndrome or Addison's disease.
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