The Cortisol Connection
Imagine walking along the sidewalk when a speeding car jumps the curb and stops just short of hitting you. In the aftermath, your heart races and your palms sweat. That’s a result of the fight or flight response, and it’s caused in part by cortisol, one of the body’s stress hormones.
“Cortisol is an important hormone across the lifespan to control metabolism, blood pressure and other important regulatory pathways,” said Dr. Fady Hannah-Shmouni, a researcher with the National Institutes of Health.
Cortisol is produced by the adrenal glands, a pair of small organs located above the kidneys. Its secretion is controlled by the hypothalamus and pituitary gland — the so-called HPA axis. When a threat occurs, the amygdala — the part of the brain that processes fear and arousal — sends a stress signal to the hypothalamus, which activates the sympathetic nervous system. This releases chemicals such as adrenaline, which causes an increase in breathing, blood pressure and perspiration.
Cortisol helps your body maintain a high state of high alert by increasing sugars in the bloodstream, helping the body to repair tissues. The hormone binds to receptors found in almost every cell of the body, including the muscles, skeleton, heart, lungs, glands and nerves. It helps fuel the muscles, increasing the odds that our ancestors could outrun a wild animal or handle other potential threats.
Cortisol also plays an important role in regulating blood pressure and inflammatory responses, affecting a type of white blood cell that seeks out and destroys bacteria, viruses, fungi, poisons and cancer cells.
However, cortisol is not just released during stressful situations. In healthy people, cortisol levels follow a diurnal rhythm, rising early in the morning and decreasing throughout the day. It regulates synapses in the brain related to learning and the ability to adapt to new situations.
“Cortisol can impact memory, provide reinforcement and prevent people from doing the same repetitive issue that may put them at harm,” Hannah-Shmouni said.
Not all stress is created equal. While chronic distress can lead to negative health outcomes, eustress (good stress) can be beneficial. A stand-up comedian might experience stage fright before trying out a new routine, for example, but it may result in a better performance.
In normal circumstances, higher cortisol levels are temporary. When cortisol is elevated for long periods of time, however, it can suppress your immune system and cause other health issues.
When cortisol is out of balance
In about one in 1 million people, the body produces too much cortisol, most often as a result of a pituitary gland tumor. This leads to a condition called Cushing’s syndrome.
People with Cushing’s syndrome experience a flushed, rounded face and weight gain in the stomach, chest and in-between the shoulder blades, resulting in a distinctive hump. It can also cause osteoporosis, high blood pressure, pink or purple stretch marks, bone loss and mood swings.
“Studies have shown patients who have Cushing’s syndrome have difficulty with memory, concentration, sleep, libido and sexual function,” Hannah-Shmouni said. “Their executive functioning is reduced compared to the normal population.”
Patients taking oral corticosteroids, such as prednisone, which are prescribed to relieve symptoms of inflammatory auto-immune diseases, may also develop Cushing’s syndrome. On the other hand, abnormally low levels of cortisol occur in Addison’s disease, an autoimmune disease that damages the adrenal glands. It causes fatigue, weight loss and skin changes. Lower cortisol levels can also cause abnormally low blood pressure.
In severe cases, the condition can result in acute adrenal failure, also known as an Addisonian crisis. This life-threatening condition causes a number of symptoms, including:
- Low blood pressure
- Higher potassium levels
- Severe weakness, pain in the lower back or legs
- Confusion and/or delirium
- Abdominal pain, vomiting and diarrhea
- Loss of consciousness
How elevated cortisol affects your body
Not everyone with elevated cortisol levels has Cushing’s syndrome. Depression, alcoholism and consistently high stress are also associated with higher cortisol levels. People who are stressed out for too long may experience headaches, stomach aches, tense, aching muscles, insomnia and low energy.
“The stress situation that triggers increased cortisol is associated with a panoply of body disfunctions at different levels in different systems,” said Dr. Ernesto Schiffrin, the physician-in-chief at Sir Mortimer B. Davis - Jewish General Hospital and director of the hypertension and vascular research unit at Lady Davis Institute for Medical Research.
Chronic stress may make people more likely to eat junk food, smoke cigarettes and overindulge in alcohol. This may lead to weight gain and increase blood pressure, which are risk factors for stroke, heart disease and diabetes.
And people who experience chronic work stress have been shown to be more than twice as likely to have metabolic syndrome — or at least three of the following: obesity, high blood pressure, elevated blood sugar, high triglycerides and low LDL cholesterol. Metabolic syndrome likewise increases the risk of heart disease, stroke and diabetes.
Stressors such as loneliness and social isolation are also associated with a higher risk of developing cardiovascular disease and stroke and greater cortisol output through the day.
How cortisol affects your brain
Elevated cortisol levels can impact the brain as well, causing insomnia, mood swings, age-related decline and problems with memory, language and cognitive function. This can disrupt natural biological rhythms, leading to unhealthy behaviors, such as avoiding exercise, making poor diet choices and neglecting sleep.
“Lack of sleep is associated with incident hypertension and of course, depression and anxiety,” Schiffrin said. Incident hypertension is the first time when someone taking medication for blood pressure receives a BP reading that indicates high blood pressure.
Consistently elevated cortisol is even more harmful for children. Growing up in an abusive home or experiencing poverty or discrimination may result in lower cognitive functioning, a suppressed immune system and harm to the areas of the brains involved in learning and memory.
What does it feel like and how is it treated?
Symptoms of elevated cortisol vary widely. They may include anxiety, depression, weight gain, thinning skin, muscle weakness, irritability, high blood pressure and headaches.
According to Dr. Richard Davidson, a professor of psychology and psychiatry and the founder and director of Center for Healthy Minds at the University of Wisconsin, chronically stressed people should consider the following lifestyle modifications:
Meditate mindfully. Mindfulness meditation is the intentional cultivation of the present moment. The goal, Davidson said, is to change your relationship with your thoughts instead of trying to suppress them entirely. “It’s really about being able to see them as thoughts rather than defining who we are,” he said. “When we can see our thoughts from some distance, that helps to change our reactivity.”
Simple mindfulness meditation can reduce cortisol activity in response to stress, plus it’s low-cost with very few side effects, Davidson added.
Get enough sleep. Davidson suggests avoiding digital devices, stimulating activities or eating and drinking (particularly alcohol) near bedtime. Experts also advise maintaining a consistent sleep schedule and sleeping in a cool, dark and quiet room.
“There is no magic bullet in terms of sleep hygiene that will work for everyone, but there are certain common-sense things we can do,” he said.
Make time for fitness. High levels of exercise have been shown to temporarily elevate cortisol, but low-intensity exercise may reduce circulating cortisol levels. “There is data showing that exercise can improve sleep,” Davidson said. And one study found that after three months of practicing yoga, cortisol levels dropped significantly in people with depression.
Should you have your cortisol levels tested?
Cortisol levels can be checked via blood, saliva, urine and hair samples. But while maintaining proper cortisol levels is important for good health and mental wellbeing, Hannah-Shmouni discouraged people who are not experiencing symptoms from having their cortisol levels checked proactively.
“Random measurements of cortisol can be all over the place depending on the stressful situation at hand,” he said, noting that the test can also give false readings.
There is still much to be learned about how stress affects the body. Hannah-Shmouni would like to better understand which steroid hormones are elevated during stressful events. “That will help shed light on not only cortisol but other adrenal precursor steroids that may be perturbated in these conditions,” he said. He pointed out that doctors have increasingly sophisticated tools to test over multiple adrenal steroids using only a small blood sample.
In the meantime, don’t let a little stress worry you too much. “It’s the persistent, continuous and repetitive rise in cortisol that leads to [harmful] effects,” Hannah-Shmouni said.