Cortisol and sleep: Do cortisol levels affect sleep?

Medically reviewed by Neka Miller, PhD on January 12, 2020. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

A number of hormones in your body are responsible for making sure you get a good night’s rest. But a hormonal imbalance can lead to several health problems, including sleep issues. In this article, we break down how one of these key hormones—cortisol, the “stress hormone”—affects your sleep-wake cycle.

So if you’ve been struggling to get a good night’s sleep lately and wonder if something might be up with your hormones, read on to learn how cortisol and sleep are connected.

What does cortisol do in the body?

One of cortisol’s main functions is regulating your body’s response to stress—hence, its name as the “stress hormone.” When you experience stress, your adrenal glands release cortisol into your body, temporarily increasing your blood sugar. This gives you the boost of energy needed to perform better in stressful situations, such as when you are in danger.

In addition to managing the stress response, cortisol also helps the body regulate a number of other important functions linked to your health.

Cortisol helps the body:

  • Respond to stress
  • Regulate metabolism
  • Control blood sugar levels
  • Maintain blood pressure
  • Reduce inflammation
  • Support the immune system

How does cortisol affect sleep?

The body’s melatonin (sleep hormone) and cortisol level (stress hormone) normally follows a regular, 24-hour circadian rhythm or pattern. Melatonin eases you into sleep—and helps you stay asleep—while cortisol helps get you up and keep you awake.

Cortisol is normally at its highest level in the morning; this morning cortisol is what helps get you out of bed in the morning. Cortisol levels then gradually drop as the day goes by. (If you’re a shift worker and you sleep during the day, cortisol levels will usually be at their highest whenever you normally get your day started—even if that’s the middle of the night.)

Melatonin normally follows an opposite pattern, with its levels reaching a peak about 3 hours before you wake up. High melatonin levels throughout the night help keep you asleep. Melatonin levels then normally fall in the morning and afternoon and begin climbing again in the evening to get your body ready for sleep.

This regular, daily rhythm of cortisol and melatonin acts like a “clock” that helps keep your body on a consistent schedule of when you’re asleep and when you’re awake. This schedule allows your body to carry out the right activities—like burning sugar to provide energy—at the right time of the day or night.

But if your cortisol and/or melatonin levels aren’t following the normal rhythm, this “clock” will stop working—and many of your body’s activities won’t happen when they should, and you may begin experiencing lower sleep quality or other sleep-related problems.

Why is my cortisol high at night?

An abnormally high level of cortisol at night may be caused by a short-term stressor (think fight or flight) or prolonged light exposure, and less screen time at night may be helpful in this situation. But there are other possible reasons why your cortisol level may be elevated at night, such as shift work—so if you’re experiencing this, it’s a great idea to discuss it with your healthcare provider.

Note that too much cortisol over an extended period of time can negatively affect your health, so it can help to be aware of this in case your cortisol levels aren’t high only at night—but are instead consistently elevated throughout the day. Not only can chronic stress cause poor sleep, but it can also lead to a number of other symptoms like weight gain, mood swings, and more.

Symptoms of chronically elevated cortisol levels can include:

  • A round, flushed face
  • Rapid weight gain (often in the face, chest, and abdomen)
  • Increased blood pressure
  • Osteoporosis
  • Changes in skin, including bruises and purple stretch marks
  • Weakened muscles
  • Mood swings, anxiety, depression, or irritability
  • Increased urination

Women experiencing chronically high cortisol levels may experience changes in their menstrual cycle and libido, in addition to poor sleep quality.

How is cortisol measured?

Cortisol is measured using urine, saliva, and blood tests. Below is a breakdown of each kind of test.

Cortisol urine test: This kind of test measures free cortisol (cortisol that isn’t attached to proteins) in your urine three to four times throughout the day. Urinary free cortisol tests are useful for checking how your cortisol levels change over a 24-hour period and can help provide insight into sleep problems, stressors, and more.

Cortisol saliva test: This test also measures the amount of free cortisol in the body, but through a saliva sample. Late-night salivary cortisol⁠—the measurement of cortisol in a saliva sample collected late at night⁠—is a reliable way to screen for Cushing syndrome.

Cortisol blood test: Blood tests measure either free cortisol or total cortisol. Blood total cortisol tests are helpful for diagnosing certain conditions, such as adrenal insufficiency in patients with critical illnesses like severe pneumonia and respiratory distress syndrome.

Checking on your cortisol levels from home

Want to get a deeper understanding of how cortisol and sleep are linked in your own body? Check on your cortisol levels and other key hormones from the convenience of home with the at-home Women's Hormone Test.

What are cortisol levels?

What is adrenal insufficiency?

Symptoms of adrenal insufficiency

Cortisol levels and stress: how cortisol levels and stress are connected

Sleep Quiz: why can’t I sleep?


1. Definition and Facts of Adrenal Insufficiency & Addison's Disease. National Insitute of Diabetes and Digestive and Kidney Diseases. URL. Accessed January 12, 2020.

2. Cortisol Test. MedlinePlus. URL. Accessed January 12, 2020.

3. Cushing syndrome. Mayo Clinic. URL. Accessed January 12, 2020.

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