Evidence check: Cortisol in the context of Müdigkeit

Cortisol is a key stress hormone with a distinct circadian rhythm. Chronic stress can dysregulate this rhythm, and both elevated and flattened cortisol patterns have been linked to fatigue. However, the evidence is mixed: many observational studies show associations, but causality is not firmly established. Single-point measurements (e.g., saliva cortisol) are highly variable and influenced by sleep, diet, and psychological state. MyBody-X does not appear to offer a specific cortisol test based on the provided context. Interpretation of cortisol in the context of fatigue should be done by a physician to rule out conditions like adrenal insufficiency or Cushing's syndrome. Evidence grade: human-moderate for association, mechanistic understanding is solid. Caveat: not a substitute for clinical evaluation.