Cortisol and Sleep: What Your Daily Rhythm Does

Cortisol is often called the "stress hormone," but it's better described as a daily-rhythm hormone that also responds to stress.

What cortisol does

Cortisol is made by the adrenal glands, under the control of the brain's hypothalamic–pituitary–adrenal (HPA) axis. It helps regulate energy, blood sugar, blood pressure, inflammation and how the body responds to stress.

Its daily rhythm

Your internal clock sets cortisol's pattern. It rises sharply in the first 30–45 minutes after waking — the "cortisol awakening response" — then gradually falls through the day, reaching its lowest point around midnight.

How sleep and cortisol interact

• Falling asleep normally dampens cortisol, and waking stimulates it.
• Short or poor sleep can modestly activate the stress-hormone system.
• Activation of that system is associated with arousal and sleeplessness.

That two-way relationship helps explain why stress and poor sleep so often go together.

What this doesn't mean

You can't tell your cortisol level from how you feel, and a website can't diagnose a hormone problem. If you have persistent sleep problems, exhaustion that rest doesn't fix, or unexplained weight change, talk with your medical provider.

How Seven Medicine approaches sleep and stress

Dr. Kristina asks about sleep, schedule, meals and stress, and may use acupuncture and individualized lifestyle suggestions as supportive care. We don't test or diagnose cortisol levels.