Cortisol's job is to prioritize survival.
Robert E. Brady, PhDCortisol is one of your body's most misunderstood hormones.
Often blamed for everything from belly fat to burnout, cortisol is much more complex than you might think.
“Cortisol is a life-sustaining hormone,” says endocrinologist Andrew R. Crawford, MD, of Dartmouth Hitchcock Medical Center (DHMC). “You really can’t live without it.”
But high cortisol levels over the long term can wear down your health, affecting everything from sleep and memory to appetite and digestion.
What makes cortisol spike?
Cortisol is a natural shield that helps your body stay alert, focused, and functional under pressure. It’s designed to increase when your body needs extra energy or alertness.
Problems can arise when cortisol is frequently elevated or remains high for long periods.
Cortisol spikes can be caused by the stress from job loss, financial worries, emotional strain, poor sleep, and trauma.
Cortisol is high when your body is in fight-or-flight mode. It can dysregulate your appetite, slow digestion, disrupt sleep, suppress your immune system, and impair thinking or memory.
“Cortisol's job is to prioritize survival and do whatever it takes to survive that external event or stressor,” says psychologist Robert E. Brady, PhD, of DHMC. “High cortisol is also going to decrease the body's functions that are less immediately necessary for survival.”
Why do you need cortisol?
Even though it’s often called the "stress hormone," cortisol is necessary for everyday health. It helps your body wake up, manage energy, fight inflammation, and respond to physical and emotional challenges.
“Cortisol affects almost every tissue in the body,” Crawford says.
Cortisol is regulated by the hypothalamic-pituitary-adrenal (HPA) axis, a system in which your brain and adrenal glands work together to control how much cortisol is produced and released.
Cortisol helps your body:
- Regulate blood sugar
- Control blood pressure
- Reduce inflammation
- Respond to stress
- Regulate the sleep-wake cycle
- Metabolize fats, proteins, and carbohydrates
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When is too much a problem?
Cortisol naturally rises and falls throughout the day. It peaks about 30-45 minutes after waking and gradually declines, reaching its lowest at bedtime.
Challenges can arise when cortisol remains high for too long from medical conditions, chronic stress, anxiety, post-traumatic stress disorder (PTSD), or long-term use of certain medications, such as prednisone.
Research suggests that chronic stress can also affect how your body regulates blood sugar, stores fat, fights infection, and even how quickly it ages.
“Our body never gets a chance to get out of that fight-or-flight situation” when experiencing chronic stress, Crawford says.
Also, traumatic events can have lasting effects and keep cortisol elevated long after the initial danger has passed, Brady explains.
“The stressor may technically end, but your perception of the threat can continue,” Brady says.
How does it affect the brain?
Chronic stress can have wide-ranging effects on the brain.
Research shows that prolonged stress and elevated cortisol may contribute to structural and functional changes in the brain, including regions involved in learning and memory.
“Chronic stress can narrow a person’s cognition, and make thinking and concentration harder,” Brady says. “It can lead people to feel overwhelmed cognitively.”
Symptoms of high cortisol
Because cortisol affects so many organs and body systems, persistently high levels can cause a wide range of symptoms.
“The body is designed to handle stressors in the short term, but when those stressors become chronic, that’s when we start to see problems with cortisol regulation and overall health,” Brady says.
Symptoms of high cortisol can include:
- Weight gain, especially around the abdomen
- Rounder face
- High blood pressure
- Elevated blood sugar
- Muscle weakness and fatigue
- Difficulty sleeping
- Anxiety or irritability
- Trouble concentrating
- Easy bruising, thin skin, slow wound healing
- Increased risk of infections
Experts point out that cortisol imbalances aren’t always caused by stress.
Cushing syndrome happens when there is too much cortisol in the body, often from a tumor or long-term steroid use. Addison’s disease is the opposite, caused by the adrenal glands not making enough cortisol. Both are rare but can cause serious symptoms, Crawford says.
Can cortisol be tested?
Doctors rely on lab tests to diagnose cortisol disorders. Tests may include:
- Late-night saliva test: Measures your cortisol before bedtime, when it should be lowest.
- 24-hour urine test: Shows how much cortisol your body makes in a full day.
- Low-dose dexamethasone test: Checks whether your body can suppress cortisol production when needed.
- Blood cortisol test: Measures cortisol in your blood at a certain time of day.
- ACTH (adrenocorticotropic hormone) blood test: Measures the hormone that tells your adrenal glands to make cortisol, helping find the cause of the problem.
“We look for a constellation of symptoms,” Crawford says. “And then we can get them set up for biochemical testing to confirm or refute the suspicion.”
Can you lower your cortisol?
For stress-related cortisol levels, lifestyle changes can help, including:
- Getting seven to nine hours of sleep per night
- Engaging in regular physical activity
- Practicing mindfulness or relaxation
- Building strong social connections
- Addressing anxiety, depression, or other mental health concerns
Brady says the best place to start when dealing with chronic stress and potentially high cortisol is your primary care provider.
Primary care providers can help identify resources that can alleviate chronic stressors, improve predictability, and restore a sense of control.
“You don’t have to figure this out alone,” Brady says. “Your primary care provider can be the first step in getting support, finding resources, and making things feel more manageable.”
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