Cortisol Serum (3 to 5 PM)

At 5 pm, cortisol is normally much lower than the early‑morning peak—about 3–10 µg/dL (roughly 80–275 nmol/L). Exact reference ranges vary by laboratory, assay and individual factors (stress, illness, sleep, medications). Persistently high or low evening cortisol should prompt medical evaluation; clinicians may use timed blood or salivary tests for diagnosis.

A serum cortisol test measures the hormone cortisol in blood to assess adrenal and pituitary function. It’s used to diagnose and monitor disorders such as Cushing’s syndrome and Addison’s disease, evaluate unexplained fatigue, weakness, weight changes and electrolyte abnormalities, investigate abnormal stress responses, and guide or monitor steroid therapy. Timing (typically morning) and additional dynamic tests may be required for accurate interpretation.

High evening (PM) cortisol indicates a disrupted diurnal rhythm and may reflect chronic stress, sleep deprivation, night‑shift work, depression, steroid use, or rarer causes such as Cushing’s syndrome or adrenal disorders. It can raise metabolic and cardiovascular risk. Clinicians typically repeat testing and may order late‑night salivary cortisol, 24‑hour urine cortisol, or imaging to determine the cause and guide treatment.

Cortisol follows a circadian rhythm and is highest in the early morning, typically peaking within about 30–45 minutes after waking (the cortisol awakening response), often around 7–9 AM. Levels then decline throughout the day, reaching their lowest point late at night and during the first half of sleep. Timing can vary slightly with individual sleep schedules.

No — cortisol normally peaks soon after waking (the cortisol awakening response) and steadily declines through the day, so levels by mid‑afternoon (around 3 PM) are usually lower. However, acute stress, exercise, caffeine, illness, or disrupted sleep can cause an afternoon rise in some people. Shift work or adrenal disorders can also alter the normal diurnal pattern; check testing if atypical.

Yes. Anxiety activates the body’s stress (HPA) axis, raising cortisol during acute episodes; chronic anxiety can cause sustained high cortisol or dysregulated (blunted) patterns. Elevated cortisol affects sleep, immune function, metabolism, blood pressure and mood, and may contribute to weight gain and memory problems. Managing anxiety helps normalize cortisol and reduces these health risks.