There are days when fatigue cannot be explained by lack of sleep alone. You wake up exhausted, have trouble concentrating, your body feels sluggish, and rest does not feel restorative. At other times, the opposite happens—you feel wired, unable to relax or fall asleep, even when you are physically tired.
In many of these cases, one hormone plays a central role: cortisol.
Cortisol is not a “bad hormone.” It is essential for life. It regulates how we use energy, how we respond to stress, how we sleep, and how the body adapts to daily demands. Problems arise when cortisol levels remain altered for prolonged periods.
In this article, we explain what cortisol is, why measuring it is important, which factors can affect it, and what information it can provide about your health.
Cortisol is a hormone produced by the adrenal glands. Its release follows a natural rhythm: levels are typically higher in the morning to help you wake up and become alert, and gradually decrease throughout the day to allow for nighttime rest.
Its main functions include:
When this balance is disrupted, the effects can be felt throughout the entire body.
Cortisol is released in response to stress. This is normal and beneficial—it allows us to react, focus, and adapt. The issue is not short-term stress, but chronic stress.
When the body remains in “alert mode” for weeks or months, cortisol levels may stay elevated or, paradoxically, become depleted and remain too low. Both scenarios can lead to symptoms.
Changes in cortisol are not always obvious, but they often present with symptoms such as:
These symptoms are not exclusive to cortisol imbalance, but they can be an important clue.
Measuring cortisol helps objectify what the body is expressing. It is a tool that allows physicians and specialists to better understand how the body is responding to stress, rest, and daily demands.
Cortisol testing may provide valuable information when:
In the laboratory, cortisol can be measured using different tests, each with specific clinical indications.
In practice, many laboratories—like ours—prioritize blood testing as the first diagnostic tool due to its simplicity, availability, and clinical value, reserving other methods for selected cases where more detailed information is required. This approach allows us to provide meaningful insights into a patient’s condition without unnecessarily complicating the process or delaying medical decisions.
Cortisol is influenced by multiple factors, including:
Ongoing worries, work pressure, personal conflicts, or sustained emotional strain.
Sleeping too little or poorly disrupts cortisol’s natural rhythm.
Physical activity is healthy, but insufficient recovery can raise cortisol levels.
The body releases cortisol as part of its defense response.
Medications
Certain drugs can affect cortisol levels.
Irregular schedules, inconsistent meals, and lack of breaks.
A laboratory result should never be interpreted in isolation, but it can help to:
Its true value lies in integrating the result with symptoms and medical history.
Cortisol testing is usually considered when:
It is not a routine test for everyone, but it is a valuable tool when there are clear indications.
Cortisol is a key hormone for understanding how your body responds to stress, rest, and daily demands. When its levels are altered, the body often sends signals that are worth addressing before discomfort becomes persistent.
If you experience symptoms such as constant fatigue, sleep disturbances, or a prolonged sense of overload, discussing them with your physician and considering cortisol testing may be a first step toward understanding what is happening and taking timely action.
Caring for your well-being begins with listening to your body and relying on trusted tools that support clarity and responsible medical care.
Like it? Share it!