Your muscles generally use glucose (blood sugar) to fuel their movements. When great effort is required, more glucose must be made available for muscles to use.
To make this happen, a cascade of hormone-driven events is triggered. You’ve probably heard of two of the most prominent hormones in this process: adrenaline and cortisol.
When Danger Is Present
When your eyes or ears (or other means of perception) detect an imminent danger, an area of your brain called the amygdala kicks in. The amygdala serves as a kind of “alarm system” that sends signals to the hypothalamus, the body’s “command center.”
Your hypothalamus tells your adrenal glands (located on top of your kidneys) to start pumping more epinephrine (another name for adrenaline) into the bloodstream. This causes a number of physiological changes to occur that help you respond to the danger.
Your heart rate increases, your blood pressure rises, glucose is released from temporary storage, and your muscles receive more blood flow. Your breathing rate also increases, allowing you to take in and circulate more oxygen. Your muscles work more efficiently, your brain becomes sharper and more alert, and your body is ready to respond.
All this can happen in seconds, allowing you to make quick decisions and take action in urgent and dangerous situations.
The Role of Cortisol
After the initial surge of epinephrine, cortisol takes over and helps to sustain the body’s response to the danger.
Cortisol increases glucose production in the liver and reduces insulin activity, making more glucose available for your muscles and brain. It also increases the availability of tissue-repairing amino acids and lipids, helping the body to recover quickly and continue working efficiently in dangerous situations.
You always have some level of cortisol in your bloodstream. Even when you’re not in danger, cortisol helps maintain several essential body functions, including regulating your sleep-wake cycle and managing how your body and brain use proteins, carbs, and fats.
Cortisol levels can spike high in response to danger and then usually return to normal when the situation resolves. But people with stressful lives can experience chronically elevated cortisol levels, which can lead to serious physical and mental health issues.
High Levels of Cortisol
Your body’s response to dangerous or stressful situations is essential for keeping you alive and safe. But it isn’t meant to be turned on all the time.
Continuing the metaphor of an alarm system, you can think of it this way: A fire alarm can be really helpful when there’s an actual fire, but if it is frequently set off without a real reason, you’ll be constantly disrupted, and you won’t know if there’s an actual emergency or just another false alarm.
In your body, just like in most social settings, non-essential functions are set aside in emergency situations. Resources are channeled away from systems like digestion, reproduction, and growth, toward services that are more urgently required, like quick decision-making, fighting, or running away.
If stress persists for an extended period of time, you’ll likely experience problems with your digestion, sleep, libido, and immune system—all those functions that adrenaline and cortisol suppress.
Reduce Your Stress Levels
This alarm system is not just triggered by physical danger. Any sort of emotional or psycho-social threat can cause cortisol levels to spike, such as financial stress, relationship problems, or an overly demanding job.
That is why it is so important that you are aware of your stress levels and be mindful in taking steps to reduce them. Stress is not just an emotional nuisance. It is directly linked to your physical well-being and can have severe consequences if left unchecked.
If you are struggling to keep your stress levels (and, therefore, your cortisol levels) in check, reach out to a therapist or medical professional. They can help you develop healthy stress-management strategies that work for you to protect yourself from the long-term consequences of elevated cortisol levels.