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What is cortisol?

Medicine & HealthLesson on requestFree to read

Quick answer

Cortisol is a hormone released by the adrenal glands that helps your body respond to stress and regulate energy, blood sugar, and inflammation. Known as the 'stress hormone', it follows a daily rhythm — high in the morning to wake you, lower at night.

Key things to understand

  1. It is produced by the adrenal glands, which sit on top of the kidneys, under the brain's control.
  2. It rises during stress, raising blood sugar and alertness for 'fight or flight'.
  3. It follows a daily curve: highest soon after waking, lowest around midnight.
  4. It also helps regulate metabolism, blood pressure, and the immune response.
  5. Chronically high cortisol from long-term stress can harm sleep, mood, and health.

People also ask

Is cortisol bad for you?
No — it is essential for waking up, handling stress, and regulating metabolism. The problem is chronically high levels from constant stress, not cortisol itself.
How can I lower high cortisol?
Regular sleep, exercise, and stress management — and treating any underlying medical cause — help bring chronically elevated cortisol back toward a healthy rhythm.
Why is cortisol highest in the morning?
A morning surge helps wake you and mobilize energy for the day, then it tapers off so levels are lowest at night for sleep.