Cortisol is the primary hormone your body releases when you’re stressed. Often called “the stress hormone,” cortisol is produced by your adrenal glands and triggers a cascade of short-term changes designed to help you survive a threat. But cortisol isn’t working alone. Your body also floods your system with adrenaline (epinephrine) and noradrenaline (norepinephrine), each playing a distinct role in how stress feels and what it does to your body.
The Two Stress Systems in Your Body
Your brain runs two parallel alarm systems when it detects a threat, and each one releases different hormones on different timelines.
The first is your fight-or-flight system. Within seconds of perceiving danger, your adrenal glands release adrenaline and noradrenaline directly into your bloodstream. These hormones hit fast: your heart pumps harder and faster, your blood pressure rises, and your liver converts stored energy into glucose so your muscles have fuel. This is why stress can make your heart pound and your hands shake almost instantly.
The second system works on a slightly slower timeline, measured in minutes rather than seconds. A region deep in your brain called the hypothalamus sends a chemical signal to your pituitary gland, which in turn signals your adrenal glands to produce cortisol. This chain reaction is called the HPA axis (hypothalamic-pituitary-adrenal axis), and cortisol is its main output. Cortisol keeps your body in an elevated state for longer than adrenaline does, sustaining higher blood sugar, altering immune function, and shifting energy away from non-essential processes like digestion and reproduction.
What Cortisol Actually Does
Cortisol’s job is to keep resources available for as long as the stressor lasts. It raises blood sugar by prompting your liver to release glucose, it suppresses inflammation in the short term, and it shifts your metabolism to prioritize immediate survival over long-term maintenance. In a healthy stress response, cortisol levels rise, you deal with the threat, and then cortisol drops back to baseline.
Your cortisol levels naturally fluctuate throughout the day even without stress. They’re highest in the morning, helping you wake up, and lowest late at night. A normal late-night salivary cortisol level is below 0.09 micrograms per deciliter. When stress pushes cortisol above its normal rhythm repeatedly, that’s when problems start.
What Adrenaline and Noradrenaline Do
Adrenaline is the hormone responsible for the immediate physical sensation of stress. It’s why a sudden scare makes your heart race before you’ve even consciously processed what happened. Noradrenaline works alongside it, narrowing blood vessels to raise blood pressure and directing blood flow toward your muscles and away from your skin and digestive system.
Together, these two hormones explain why acute stress feels so physical. The tight chest, the jittery energy, the tunnel vision, the dry mouth: all of these are adrenaline and noradrenaline preparing your body to fight or run. These effects fade relatively quickly once the threat passes, usually within 20 to 60 minutes.
Other Hormones Involved in Stress
Beyond the big three, your body releases several supporting hormones during stress. Vasopressin (also called antidiuretic hormone) helps regulate how much water your kidneys retain, keeping your blood volume and pressure stable during a crisis. Research in the Journal of Endocrinology has shown that vasopressin also amplifies the cortisol-releasing signal in your brain, making the stress response stronger. Its role becomes especially important during chronic or repeated stress.
Your body also produces protective hormones that help counterbalance cortisol. DHEA, a hormone made by the same adrenal glands that produce cortisol, has a protective role during acute stress by directly antagonizing some of cortisol’s effects. Oxytocin, often associated with bonding and social connection, appears to peak before cortisol reaches its maximum during a stress response, helping to speed up recovery and bring the HPA axis back to baseline.
When Stress Hormones Stay Elevated Too Long
The stress hormone system is built for short bursts. A threatening situation triggers the response, cortisol and adrenaline do their jobs, and then levels return to normal. The problem is that modern stressors, like financial pressure, caregiving responsibilities, or chronic work demands, can keep these hormones elevated for weeks, months, or years.
Chronically elevated cortisol takes a measurable toll on the immune system. Under normal circumstances, cortisol acts as an off switch for inflammation, shutting down the production of inflammatory molecules after an infection or injury. But research from the American Psychological Association found that people under chronic stress lose this regulatory ability. Their immune cells become less sensitive to cortisol’s signals, meaning inflammation persists unchecked. In one study, parents of children with cancer showed significantly diminished sensitivity to cortisol’s immune-regulating effects compared to parents of healthy children.
This immune disruption helps explain why people under long-term stress get sick more often, heal more slowly, and are more vulnerable to conditions driven by inflammation. Sustained cortisol elevation is also linked to weight gain (particularly around the midsection), disrupted sleep, difficulty concentrating, and mood changes including anxiety and depression. Over time, the same hormone that protects you in a crisis becomes a source of damage when it never turns off.
How the Stress Cascade Works Step by Step
The full sequence from threat to hormone release follows a precise chain. Your brain’s hypothalamus releases a signaling molecule called CRH (corticotropin-releasing hormone). CRH travels to your pituitary gland, where it binds to specific receptors and triggers the release of ACTH (adrenocorticotropic hormone) into your bloodstream. ACTH then travels to your adrenal glands, sitting on top of your kidneys, and stimulates them to produce cortisol.
This chain has a built-in brake. Once cortisol levels in your blood rise high enough, cortisol itself signals back to the hypothalamus and pituitary to stop producing CRH and ACTH. This negative feedback loop is what brings cortisol back down after a stressor ends. In people with chronic stress, this feedback loop can become less effective, keeping cortisol elevated even when no immediate threat is present.
Meanwhile, the adrenaline pathway bypasses this chain entirely. Your brain sends nerve signals directly to the inner part of your adrenal glands, which dump adrenaline and noradrenaline into your bloodstream within seconds. This is why adrenaline hits you so much faster than cortisol: it doesn’t need to go through a multi-step hormonal relay.