Cortisol: What the Stress Hormone Does in Your Body
Cortisol is often called a bad hormone. In truth you could not live without it — the trouble only starts when it stays high for a long time.
But · 5 min read · Sep 5, 2026
Cortisol is a hormone released by the adrenal glands, two small glands sitting on top of the kidneys. It takes part in regulating blood sugar, blood pressure, inflammation and the way the body uses energy. In other words, cortisol is what helps you cope with pressure.
Cortisol has its own rhythm through the day. It is usually highest in the morning to wake the body up, then falls gradually and reaches its lowest point at night. This rise and fall is closely tied to sleep.
When stress goes on and on
A short spell of stress is normal and useful. The problem is when the pressure never lets up: work piling on, worry about the family, months of poor sleep. Cortisol then stays high for a long stretch, and the body pays for it.
- Blood sugar tends to run higher even though you are not eating more
- Blood pressure creeps up
- Sleep gets worse, forming a vicious circle with the stress
- Fat gathers more easily around the abdomen
- Resistance to infection drops, so minor illnesses come more often
- Mood turns irritable, concentration is harder, and tiredness drags on
What usually helps
Put sleep first, because it is the strongest lever you have. Regular, moderate exercise also helps the body regulate itself better — but training hard while you are already exhausted works against you.
Breathe slowly and deeply for a few minutes, walk outdoors, talk with the people close to you, and cut back on news and social media before bed. These sound like very small things, but they genuinely work as long as you do them regularly.
When to see a doctor
Genuine cortisol disorders are uncommon, but they do exist. See a doctor if you gain weight quickly, concentrated in the face and abdomen while your arms and legs grow thinner; if your skin is thin and bruises easily, with purple stretch marks appearing; if you have clear muscle weakness; or if your blood pressure or blood sugar rises in a way that is hard to explain.
In the other direction, see a doctor if you have severe tiredness that goes on, loss of appetite, weight loss, faintness on standing up, or skin that is turning darker.
You should also see a doctor if you are taking corticosteroid medication long term, or if stress and poor sleep are clearly affecting your daily life.
This information is for general reference only and does not replace advice from your doctor.
