What Is Cortisol? Everything You Need to Know About the Body’s Stress Hormone
What Is Cortisol?
Cortisol is a steroid hormone produced by the adrenal glands, which sit on top of each kidney. Your body releases cortisol throughout the day, with levels typically highest in the morning and gradually declining at night.
PIH Health Endocrinologist Christian John Gastelum MD states, “This hormone helps your body respond to challenges, whether that’s a looming deadline, a workout, an illness, or a perceived threat. When cortisol levels are balanced, it supports overall health. When levels are too high or too low for long periods of time, problems can arise.”
What Does Cortisol Do in the Body?
Cortisol affects nearly every system in the body. Some of its most important roles include:
- Helping the body respond to stress and perceived danger
- Regulating blood sugar and energy production
- Supporting metabolism, blood pressure, and heart function
- Reducing inflammation and influencing immune responses
- Supporting the sleep-wake cycle and early development
Cortisol is also a major part of the body’s fight-or-flight response, which increases energy and alertness in threatening situations.
What Triggers Cortisol Release?
“Cortisol production is regulated by communication between the brain and adrenal glands,” says Dr. Gastelum. When the body senses stress or imbalance, signals are sent that prompt cortisol release.
- Emotional or psychological stress
- Physical stress such as illness, injury, or intense exercise
- Poor sleep, shift work, or disrupted routines
- Extreme temperatures, infections, and certain health conditions
Because cortisol follows a daily rhythm, ongoing lifestyle stressors can interfere with its natural pattern.
Normal Cortisol Patterns
In a healthy body, cortisol levels follow a predictable cycle:
- Highest in the early morning to help you wake up
- Gradually decreasing throughout the day
- Lowest at night to support rest and recovery
Disruptions such as chronic stress, poor sleep, or long-term night shift work can throw this rhythm out of balance.
What Happens If Cortisol Levels Are Too High?
Short-term increases in cortisol are normal and helpful. However, chronically elevated cortisol can affect both physical and emotional health.
Common signs of high cortisol include:
- Weight gain, especially around the abdomen and face
- Acne, thinning skin, and easy bruising
- Muscle weakness, fatigue, and headaches
- Difficulty sleeping and trouble concentrating
Emotionally, high cortisol may contribute to anxiety, depression, mood swings, irritability, and a lower sex drive. In rare cases, persistently high cortisol may be linked to underlying adrenal or pituitary issues.
What Happens If Cortisol Levels Are Too Low?
Too little cortisol is less common but can still cause noticeable symptoms, such as:
- Constant fatigue and muscle weakness
- Loss of appetite or unintentional weight loss
- Nausea, abdominal discomfort, or low blood pressure
- Difficulty concentrating
Some people may also experience salt cravings or changes in skin pigmentation.
How Are Cortisol Levels Measured?
Cortisol levels can be measured through:
- Blood tests
- Saliva tests, often done at night
- Urine tests collected over a 24-hour period
Because cortisol fluctuates throughout the day, testing may involve specific timing or multiple samples.
Can You Lower Cortisol Naturally?
Rather than trying to “hack” cortisol, the most effective approach is supporting overall stress regulation. Dr. Gastelum suggests these helpful strategies:
- Prioritizing consistent, quality sleep
- Staying physically active without overtraining
- Eating balanced meals that support stable blood sugar
- Practicing stress-management techniques like mindfulness
- Creating healthy boundaries around work and rest
Despite popular claims, many supplements marketed for cortisol reduction lack strong scientific support.
The Bottom Line
Cortisol is a vital hormone that helps the body function, adapt, and recover. While short-term increases are a normal part of responding to stress, ongoing imbalance linked to chronic stress, poor sleep, and disrupted routines can affect long-term health. Understanding how cortisol works allows you to make more informed lifestyle choices and better support balance, helping the body stay resilient and thrive. If you’re experiencing ongoing stress, fatigue, or other symptoms that may be related to cortisol, talk with your doctor or schedule an appointment with a PIH Health provider at PIHHealth.org/Appointments
