The HPA axis stress hormone — peaks early morning. Low AM cortisol signals adrenal insufficiency; high signals chronic stress or HPA dysfunction.
Cortisol follows a strong diurnal rhythm — peaks around 30 minutes after waking, drops through the day, bottoms around midnight. The morning peak is what's typically measured, drawn between 7–9 AM for standardization.
Low morning cortisol can indicate adrenal insufficiency (Addison's), pituitary problems (secondary), or HPA axis exhaustion from chronic stress. Persistently elevated cortisol points to acute stress, sleep deprivation, depression, Cushing's syndrome, or exogenous corticosteroid use.
Cortisol is influenced by: time of day (huge — must standardize draw time), acute stress (psychological + physical), sleep quality and duration, infection/inflammation, exogenous corticosteroids (suppress endogenous), opioids, pregnancy, oral contraceptives (raise CBG, raising total cortisol), and pharmacologic agents — metyrapone and ketoconazole lower it; ACTH stimulates it.
For optimization users, AM cortisol gives a snapshot of HPA tone. Chronically elevated cortisol on training-heavy weeks signals overtraining or insufficient recovery — pair with HRV trends. Low cortisol with fatigue + low blood pressure warrants adrenal workup with your provider. Some peptide protocols (high-dose GHRP-2/6) can transiently elevate cortisol; ipamorelin avoids this.
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Start tracking →Informational only — not medical advice. Reference ranges vary by lab and individual context. Work with a licensed provider to interpret your specific results.