Hormones
Cortisol
What it is
Cortisol is a hormone from the adrenal glands involved in the stress response, metabolism and the sleep-wake cycle. It follows a clear daily rhythm - typically highest in the morning and lowest late at night.
Why it matters
Because of that rhythm, timing matters enormously: a level is only meaningful relative to when it was taken. Persistent extremes can reflect adrenal or pituitary issues, which is why unusual results are followed up rather than acted on directly.
What “optimal” looks like
There is a time-of-day-specific healthy range rather than a single number. Morning samples are standard; clinicians interpret cortisol with the collection time and your symptoms.
This is general information, not medical advice or a diagnosis. Always discuss your results with a qualified clinician.
See your own Cortisol
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