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.
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Cortisol, also known as the “stress hormone,” plays a key role in your body’s response to stressful situations. However, cortisol also helps regulate a number of other important functions, like your immune system and metabolism. Having too much or too little cortisol in your body can be harmful to your health, which is why it’s important to find effective ways to manage the stress in your life.
Want to understand more about cortisol and how different cortisol levels can affect one’s health? We break down how cortisol impacts your body and the symptoms associated with high cortisol or low cortisol in this article—so read on to learn more.
One of cortisol’s main functions is regulating your body’s response to stress—hence, its nickname of the “stress hormone.”
When you experience stress, your adrenal glands release cortisol into your body which temporarily increases your blood sugar for a boost of energy and curbs nonessential functions. This process helps you perform better in stressful situations, such as when you are in danger.
When your body experiences a cortisol imbalance, the amount of cortisol produced in response to any kind of stress can impact important functions in your body as a result of too much or too little cortisol being secreted.
In addition to managing your stress response, cortisol also helps your body regulate a number of other key functions linked to your health.
In normal amounts, cortisol helps your body:
Read more about how cortisol levels affect sleep in another blog post.
What are cortisol levels normally like throughout the day? Cortisol levels are normally highest in the morning, which helps you wake up from sleep. Then, as the day goes by, they gradually drop until your body experiences its lowest levels of cortisol around the time when you go to bed. Note that if you’re a shift worker with a schedule where you sleep during the day, your cortisol levels will usually be at their highest whenever you normally get your day started—even if that’s the middle of the night.
Cortisol levels throughout the day can also change in response to short-term, or acute, stressors. Acute stress—like finding yourself stuck in traffic—can cause a large spike in cortisol at that particular point in the day, with the rest of the day's levels following the normal pattern.
Urine, saliva, and blood tests are all widely used methods for checking cortisol levels in your body.
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’s syndrome (a condition involving high cortisol levels in the body).
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.
When the adrenal glands fail to produce enough cortisol in your body, this is known as hypocortisolism or adrenal insufficiency. Adrenal insufficiency has 3 different categories:
Primary adrenal insufficiency (Addison’s disease): A condition resulting from damage to the adrenal cortex, preventing the adrenal glands from properly functioning and leading to decreased cortisol production. In the United States, it’s most commonly caused by immune system malfunction, but other possible causes include infection and cancer. Symptoms can include weight loss, muscle loss, fatigue, mood swings, and changes in the skin.
Secondary adrenal insufficiency: A condition caused by the pituitary gland failing to secrete enough of the hormone ACTH—the hormone that tells the adrenal glands how much cortisol is needed—which causes a decrease in cortisol production. An adrenocorticotropic hormone test, or ACTH stimulation test, can help identify if you may be experiencing primary and secondary adrenal insufficiency (AI).
Tertiary adrenal insufficiency: A condition where the hypothalamus (the region in your brain that links the nervous system and the endocrine system through the pituitary gland) releases an inadequate amount of the hormone CRH—the hormone that tells the pituitary gland to produce ACTH.
Want to learn more about what adrenal insufficiency is? Check out our post “What is adrenal insufficiency?”
Although cortisol is an essential hormone that supports several important functions in your body, having too much of the hormone over a prolonged period of time can lead to major changes in your metabolism and can be harmful to your health.
A temporarily high cortisol level is often beneficial in the short-term because it can help you more effectively cope with acute stressors. But having a high cortisol level over a prolonged amount of time—often the result of experiencing chronic or long-term stress—can have negative impacts on your health. Note that there are other possible causes for chronically high cortisol levels beyond long-term stress, including pituitary tumors and certain types of medication like steroids.
For a fuller breakdown, read about the symptoms of high cortisol levels in the body.