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0What is cortisol—and should you actually be worried about it?
TIME | By Angela Haupt| 654 words | ★★★☆☆
Myths about cortisol—also known as the “stress hormone”—abound on social media. Here’s what experts say about this substance that helps make your body tick.
You know the feeling: your body is drained, your eyes are heavy, but the moment your head hits the pillow, your mind starts racing. You’re clearly tired, yet sleep feels impossible. In many cases, the culprit may be cortisol, the hormone best known for helping the body respond to stress.
Cortisol is often called the “stress hormone,” but that nickname only tells part of the story. Produced by the adrenal glands above the kidneys, cortisol is essential for life. It helps regulate metabolism, immune function, inflammation, blood sugar, and the sleep-wake cycle. “Honestly, we cannot do without it,” says Dr. Anat Ben-Shlomo, an endocrinologist and associate professor of medicine at Cedars-Sinai.
Under normal circumstances, cortisol follows a daily rhythm. Levels peak in the early morning, helping us wake up and feel alert, then gradually decline throughout the day, reaching their lowest point at night so the body can rest. Problems arise when stress keeps cortisol elevated into the evening.
When the body perceives a threat—whether physical, emotional, or psychological—the nervous system activates a chain of hormonal responses, including the release of cortisol. This response is useful in emergencies because it provides energy and sharpens focus. But when stress becomes chronic, the body may remain in a prolonged state of alertness.
This is why people often feel “wired but tired.” They may be physically exhausted, but elevated cortisol keeps the brain vigilant, making it difficult to relax and fall asleep. High nighttime cortisol can also cause frequent awakenings and lighter, less restorative sleep.
Sleep and cortisol are closely linked. Poor sleep raises cortisol levels, and high cortisol further disrupts sleep, creating a vicious cycle. According to experts, this cycle can affect memory, mood, and overall health.
Cortisol has become a popular topic on social media, where it is blamed for everything from weight gain to fatigue and anxiety. Some influencers claim that chronic stress causes “adrenal fatigue,” a condition in which the adrenal glands supposedly become too exhausted to produce enough cortisol.
However, endocrinologists say adrenal fatigue is not a recognized medical diagnosis. A 2016 review of scientific studies found no evidence that the condition exists. Dr. Anne Cappola of the University of Pennsylvania notes that the adrenal glands have significant reserve capacity and rarely “burn out.”
That does not mean cortisol disorders are imaginary. Rare but serious conditions do occur.
Too much cortisol can result in Cushing’s syndrome, often caused by tumors affecting hormone production. Symptoms may include weight gain, muscle weakness, bruising, and blood sugar problems.
Too little cortisol can lead to Addison’s disease, an autoimmune disorder in which the body attacks the adrenal glands. Symptoms include severe fatigue, dizziness, appetite loss, and darkening of the skin.
Although these disorders are uncommon, their symptoms overlap with more familiar problems such as anxiety, perimenopause, and sleep deprivation. For persistent symptoms, doctors recommend medical evaluation rather than self-diagnosis or unproven supplements.
Even without a medical disorder, chronic stress has real health consequences. Research links prolonged stress to depression, obesity, cardiovascular disease, and stroke. High cortisol over time may contribute to inflammation, impaired immunity, and cognitive difficulties.
The good news is that lifestyle habits can help regulate the body’s stress response. Specialists recommend regular exercise, balanced nutrition, mindfulness or meditation, and consistent sleep schedules. Reducing caffeine late in the day, limiting screen exposure before bed, and practicing relaxation techniques can also help lower evening cortisol.
In other words, if you feel completely exhausted but still can’t fall asleep, your body may be signaling that stress—not lack of tiredness—is keeping you awake.
Cortisol is not the enemy. It is one of the body’s most important survival tools. But when stress keeps this system switched on at the wrong time, it can leave us trapped in a state of fatigue and sleeplessness.
As Dr. Ben-Shlomo puts it, the adrenal glands are remarkably resilient. The real challenge is learning how to calm the stress that keeps them working overtime.
