Most people have heard about the hormone cortisol in conjunction with the fight or flight response triggered by the brain when we’re scared…or running for our lives, as our ancestors might have.

Another easy way to understand the fight or flight response is an example from the animal kingdom, like when an antelope spots a pride of hungry lions across a vast grassland. The antelope’s brain recognizes the threat and sends signals to provoke a cascade of changes in its body, including releasing cortisol into the blood to energize and prepare it to face the predator or, more realistically, to attempt to escape.1

But while the antelope example provides a general explanation of how the body responds to stress or fear, it doesn’t do cortisol justice. In fact, even though cortisol is often called the stress hormone, in truth, it is so much more than that.2

What Is Cortisol?

The job of every hormone is to send messages to different parts of the body. The messages they send and where they send them to depend on which type of hormone we are talking about. Insulin, for example, keeps your blood sugar under control, while melatonin tells your body when it’s time to go to sleep. Most hormones are created within small organs called glands, and the main job of these glands is usually to produce and release specific hormones into the bloodstream so they can take their messages where they’re supposed to go.3,4

Cortisol is made in your two adrenal glands—there’s one atop of each kidney. The adrenal glands know when to make and release cortisol based on a sort of ongoing conversation between two different parts of the brain: the pituitary gland and the hypothalamus. Together, the adrenal glands, the pituitary gland, and the hypothalamus are called the HPA axis.

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Stress is not the only reason the adrenal glands are told to release cortisol—the pituitary gland and the hypothalamus are constantly checking up on the levels of cortisol in your blood to make sure there isn’t too much or too little. When it is too little, they send signals to release more, and when it is too much, they put the brakes on these signals.5

The cortisol level in your body naturally fluctuates over the course of the day in a rhythm set by the brain. “There are times in the day that cortisol is very low and times when it goes up quite high,” explains John Marshall, MD, PhD, the Andrew D. Hart Professor of Medical Science and the director of the Center for Research in Reproduction at the University of Virginia in Charlottesville. “It starts to go up between two and three in the morning and has a peak somewhere between eight and nine in the morning, and then gradually declines during the day (with one or two small increases) until about four or five in the afternoon, when the levels are very low and stay that way up until two a.m. comes back around.”

What Does Cortisol Do?

There are trillions of cells in your body, and a majority of them have receptors for cortisol, meaning that cortisol can bind to almost any cell and change how it functions. This is why cortisol is so important—it plays a role in essentially every system in the body.6,7

Eva Redei, PhD, professor of psychiatry and behavioral sciences and physiology at Northwestern University Feinberg School of Medicine in Chicago, says that cortisol is “really the water of life” because, like water, cortisol goes everywhere in the body.

Main Cortisol Functions

While it would be difficult to name all of the functions of cortisol, here are some of its prime responsibilities:

  • Cortisol prepares the body to deal with stress or danger. 7
  • Cortisol helps control blood sugar and blood pressure. 7
  • Cortisol regulates how the body uses food and gets energy—your metabolism. 7
  • Cortisol plays a role in helping the brain form memories. 6
  • Cortisol helps the body recognize when it is time to sleep and when to wake up. 5

There also are likely many minor and subtle effects of cortisol that we don’t yet fully understand, according to Dr. Marshall.

How Cortisol Impacts Mental Health

To explain how cortisol can affect mental health, let’s go back to the scenario where the antelope encountered a pack of hungry lions. Now, in this day and age, most people aren’t encountering wild animals on a daily basis. But while the circumstances around us are different from an antelope or our ancient ancestors, our brains are still trained to respond to threats. They have been calibrated to view modern fears and anxieties similar to the sight of a hungry lion. But today, the fight or flight response is more likely to come from situations such as giving a presentation, going to a party, or even just thinking about something that makes you anxious.1

Fight or Flight

For the most part, fight or flight—otherwise known as acute stress—is a good thing. If you suddenly see a car swerving into your lane and your body triggers a stress response, you will be able to respond quickly and maneuver out of the way. And even when the body responds this way to a non-threatening situation, like playing tennis with a friend, it can still be beneficial because it gets you geared up to perform at full capacity.

Problems begin when acute stress is triggered by societal or mental stressors rather than physical stressors, as commonplace as paying your bills, sitting in traffic, or even responding to an email. Your body is prepared to act, but there’s not much it can do to get away from the perceived threat.

Your heart rate and blood pressure are elevated, and your body is in overdrive in preparation, but there’s no tangible predator to fend off, and you’re left depleted. While fight or flight is activated, all of your energy is directed toward the threat, and many other bodily functions that are nonessential at the moment are slowed or halted.2,8

And problems worsen when that acute stress turns into chronic stress. Fight or flight is a process that’s meant to be fleeting: After escaping or dealing with the situation, the body is supposed to return to its normal state. Cortisol and other hormone levels, blood pressure, and heart rate are all supposed to go back to a resting state, and systems like digestion that were not essential for survival at the time get back to work.2

Chronic Stress Conditions

Chronic stress is when your fight or flight response gets activated too often or stays on for too long. The wear and tear that chronic stress puts on your body is linked with numerous mental and physical health issues, including:2

  • Anxiety
  • Depression
  • Digestive issues
  • Headaches
  • Heart problems
  • Difficulty sleeping
  • Gaining weight
  • Problems with memory and concentration

In part, the prolonged high cortisol levels prompted by chronic stress are thought to cause these problems.5

“We think that our minds and bodies weren’t designed to have that system of stress response, which includes cortisol, turned on so frequently,” says Neda Gould, PhD, an assistant professor of psychiatry and behavioral sciences and the associate director at Johns Hopkins Bayview Medical Center Anxiety Disorders Clinic in Baltimore.

While the relationship between cortisol and the development of mental health issues isn’t completely clear-cut, “it is safe to say that chronic stress can make us vulnerable to the development of psychiatric illnesses,” says Gould.

Studies on this topic have revealed differing findings concerning whether high cortisol, low cortisol, or just a poorly regulated cortisol clock is linked to mental health issues like depression, bipolar disorder, anxiety, post-traumatic stress disorder (PTSD), and substance use disorders.9

“Mental health changes are something that may be a consequence of an excess or absence of cortisol, but it is unlikely to be the primary cause,” says Dr. Marshall. “The cause and effect are quite unclear.”

Gould sums up the relationship between cortisol and mental health this way: “I think that the most important takeaway at this point is that it’s a relationship that’s not fully understood.”

What Happens When Cortisol Levels Are Too High Or Too Low?

While we don’t exactly know the link between high or low cortisol and mental health issues, we know of specific health issues that can develop due to low or high cortisol levels.

High Cortisol Levels

When you have too much cortisol in your body over a long period, a disorder called Cushing’s syndrome can occur. Cushing’s syndrome most commonly develops when people take medications called glucocorticoids at high doses for a long time. Glucocorticoids are synthetic drugs similar in structure and function to the cortisol that is naturally produced in the body. In pill form, these drugs are used to treat conditions like asthma, rheumatoid arthritis, and lupus, and can also be injected to treat pain, like joint pain or back pain.10

It’s also possible to develop Cushing’s syndrome if your body is overproducing cortisol due to a tumor, whether cancerous or noncancerous. For example, a noncancerous tumor in the pituitary gland can cause an increase in the signals that tell the adrenal glands to make cortisol, thus increasing cortisol production.10

Some of the signs and symptoms of Cushing’s syndrome are gaining weight or changes in the way your weight is distributed, like more fat in the face, neck, and shoulders, but thinning the arms and legs. Thinning and slow-healing skin, purple-colored stretch marks on the skin, easy bruising, and acne are other common symptoms. If Cushing’s syndrome is left untreated, it can lead to much more severe complications and can even be fatal.10, 11

Interestingly, depression is very prevalent among people with Cushing’s syndrome, another piece of the puzzle between high cortisol levels and mental health. “In Cushing’s syndrome, people experience significant mood changes,” explains Dr. Marshall. “Even after it’s treated, the depression aspects persist not uncommonly for up to a year or more. So there are significant happenings in the central nervous system that we don’t fully understand.”12

Low Cortisol Levels

On the other hand, when the adrenal glands aren’t making enough cortisol and other hormones, people can develop adrenal insufficiency or Addison’s disease. These conditions can start when the adrenal glands’ ability to produce cortisol is affected or because the signals telling the adrenal glands to produce cortisol are lowered.

People with adrenal insufficiency or Addison’s disease may experience symptoms like fatigue, weakness in their muscles, poor appetite, weight loss, and stomach pain. Severe complications and even death can occur if Addison’s disease is not treated. Adrenal insufficiency is also linked to mental health issues, like memory problems, depression, and psychosis.13, 14, 15

All told, the fact that too much or too little cortisol is associated with mental health issues reveals that the right amount of cortisol is a delicate balance. Problems likely arise when that balance is thrown off-kilter.

Can Cortisol Levels Be Tested?

Doctors can figure out how much cortisol is in your body with tests that measure levels in saliva, urine, blood, and even hair. However, because cortisol levels change throughout the day, testing may only give you a snapshot of the cortisol levels at the moment of the test. That’s why tests may need to be done multiple times in a day.

In the case of urine tests, patients will usually need to collect their urine over 24 hours. On the other hand, because hair grows more slowly, the amount of cortisol in hair can be tested to see how much cortisol has been circling in the body over a more extended period—up to several months. More recently, scientists have been working on developing wearable sensors that can monitor cortisol levels.7, 16, 17

Cortisol tests are typically done to determine if someone has either abnormally high levels of cortisol and may have Cushing’s syndrome or abnormally low levels of cortisol and may have Addison’s disease or adrenal insufficiency.7

If you’re worried about your cortisol levels for other reasons, such as chronic stress or mental health issues, you can ask your doctor about cortisol testing. However, at this point, measuring cortisol levels is not a significant part of diagnosing or treating these problems.

“I think there are many people who think ‘my cortisol levels are elevated, and I need to decrease them,’ but I think that what they’re saying is they’re in that fight or flight mode, and they can’t get rid of those symptoms,” Gould says. “And I don’t think that connection has been made or reliably brought to patient care that we would say, ‘yeah, I think your cortisol levels are high. Let’s do X, Y, and Z to bring them down.’ What we say is, ‘yeah, you are stressed, so let’s do X, Y, and Z to reduce those symptoms of distress.'”

How Can You Lower Or Balance Your Cortisol Levels?

Chronic stress is the main factor known to increase your cortisol levels, but what you eat and how much you sleep also play a role. These lifestyle habits and factors can all elevate cortisol:16

  • Drinking alcohol
  • Too little sleep
  • Eating a diet rich in refined carbs and sugar (foods with a high glycemic index)
  • Inflammation
  • Pain

Many of these factors are often wrapped up together, triggering an unhealthy cycle of eating poorly, not sleeping enough, and being chronically stressed. Therefore, the best way to balance your cortisol levels is to reduce your stress, in part by cutting out unhealthy lifestyle choices and increasing healthy ones.16

There are many ways to relieve stress, and some have been linked to a decrease in cortisol in various studies. However, it’s important to remember that cortisol is only one part of the way our bodies react to stress, and most studies on this topic only provide a potential link between stress-relieving strategies and lower cortisol levels, not a definitive connection.

Cortisol and Stress: 8 Stress Relievers

That being said, here are some stress-relieving techniques to help you balance the cortisol levels in your body:

  • Get plenty of sleep. Proper sleep is key to reducing stress. Since sleep deprivation is associated with an increase in cortisol levels, if you get quality sleep, your cortisol levels will likely thank you. Aim for 7 to 8 hours of deep, quality sleep per night. If sleep doesn’t come easily to you, this may sound like a big ask, but there are a lot of ways to go about improving your sleep. For starters, try to adhere to a strict sleep schedule by going to bed and waking up at the same time every day (yes, this includes weekends) and avoiding daytime naps.18, 19, 20
  • Do things you enjoy. Maybe it’s spending time with a pet—one study found that interacting with cats and dogs may lower people’s cortisol levels. In another study, making art had a similar effect (and you don’t need to be an artist either to enjoy the benefits).21,22
  • Get outside. According to some studies, spending time in nature could also be a good option for stress relief and cortisol reduction. It may be that the benefits of getting outside have to do with exposure to sunlight. Light therapy, which is sometimes used to treat conditions like seasonal affective disorder (SAD) or depression, may have a beneficial effect on regulating cortisol levels. However, research on this is inconclusive.23
  • Try meditation and breathing exercises. There’s no harm—and potentially a lot of good—in using meditation and other relaxation techniques to relieve stress. Various studies have found a potential benefit of deep breathing exercises and mindfulness meditation for stress reduction and healthy cortisol levels. If you’re not a practiced meditator, don’t worry—no matter which type of meditation or breathing technique you choose, the important thing is that you spend time relaxing and clearing your mind. Even just a couple of minutes of peace and calm can be beneficial for your mental state.24, 25, 26
  • Dive into yoga and other forms of exercise. We all know that exercise is excellent for both your mental and physical health. Its stress-relieving capabilities may even lower your cortisol levels, although evidence is limited. In particular, one analysis of 42 studies found that practicing yoga may be linked to lower cortisol levels, blood pressure, and heart rate. You can’t really go wrong in choosing an exercise type—anything from low-impact yoga to long-distance running can boost your mood and lower your stress, so find something you enjoy. While 30 minutes of daily exercise is a good goal to set, it’s better to get some activity in than none at all.27, 28, 29, 30
  • Eat a healthy diet. The best advice is to stick with a balanced diet rich in fruits, vegetables, and other plant-based foods. Some studies may have found some cortisol-reducing benefits from tea, chocolate, and fish oils, but the results tend to be uncertain, and it’s much better to focus on improving your diet overall rather than focusing on only specific foods. Avoiding foods with a high glycemic index (like refined sugar and carbs) may also be helpful, as these types of foods have been shown to raise cortisol levels.31, 16
  • Reach out for social support. Spend more time with your friends, colleagues, and family members, and build deeper connections with them to harness the potential power of social support in reducing stress. According to one study, laughing may also help.32, 33
  • Seek professional help. If you’re having trouble getting your stress under control, a professional therapist or mental health counselor can be immensely helpful. Working with a therapist can help you identify what is causing your stress and develop actionable, stress-reducing strategies.2


How can you lower cortisol?

If your cortisol is too high due to Cushing's syndrome, a serious condition caused by too much cortisol, you'll need to work with a doctor to treat the problem correctly and lower your cortisol levels. However, if you're worried about your cortisol levels because you're stressed out and feel like you're in a constant state of fight or flight, the best way to solve the problem is to reduce your stress. Only you can know what's really going on in your life that's causing you to stress, and therefore you are your own best advocate. Some of the common ways to relax and cut out stress are exercising, getting more and better quality sleep, leaning on friends and family, seeking support from a therapist, and doing more of the things you love.2

Where is cortisol produced?

Cortisol is a hormone produced in the adrenal glands, two triangular-shaped glands, one atop each kidney. The adrenal glands release cortisol into the blood at specific times a day, in accordance with a sort of internal clock that regulates cortisol levels. These glands receive signals from the brain's pituitary gland that tell them when to make and release cortisol.5

What causes cortisol to increase?

Stress and unhealthy lifestyle habits, like alcohol consumption, too little sleep, and a high glycemic diet, are thought to be some of the primary drivers of harmfully high cortisol levels. However, cortisol is by no means all bad. It’s an essential part of how our bodies function and having too little cortisol can be just as harmful as having too much. Like many things in life, balance is key.16<

How do you measure cortisol?

You probably don't need to test your cortisol levels unless you are concerned about a medical condition like Cushing's syndrome or Addison's disease. Your doctor can measure your cortisol levels by testing samples of your blood, saliva, hair, or urine. These tests will need to be done at specific times to determine if your cortisol levels are truly abnormal, as they fluctuate at various times during the day and night. There may be over-the-counter cortisol tests available, but it's always best to visit your doctor to ensure accuracy.

What type of hormone is cortisol?

Cortisol is a steroid hormone. Other examples of steroid hormones include sex hormones like testosterone and estrogen. Hormones are grouped into specific types based on their structure, function, and where they are produced. Because cortisol receptors are almost everywhere in the body, cortisol is essential to life and plays a role in most bodily systems and functions.34

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Last Updated: Aug 9, 2021