Stress and Cortisol: Understanding Your Body's Response

We talk about stress constantly - we feel stressed, we are stressed, everything is stressful. But what is actually happening in your body when you experience stress? And why does chronic stress seem to affect so many different aspects of health, from your digestion and sleep to your weight and mood?

The answer involves a complex cascade of hormones and physiological changes, with cortisol playing a central role. Understanding this system helps explain why stress management is not just about feeling calmer - it is genuinely foundational to your physical health.

The Stress Response: Designed for Survival

Your stress response exists for a very good reason: survival. When your ancestors encountered a predator, their bodies needed to react instantly - increasing heart rate, sharpening focus, directing blood to muscles, and suppressing non-essential functions like digestion. This fight-or-flight response saved lives.

Here is how it works: When your brain perceives a threat (real or imagined), it signals your adrenal glands to release stress hormones - first adrenaline for the immediate response, then cortisol to sustain the alert state. These hormones trigger a cascade of changes:

• Heart rate and blood pressure increase
• Blood sugar rises to provide quick energy
• Breathing becomes faster and shallower
• Muscles tense, ready for action
• Digestion slows (not a priority when running from danger)
• Immune function shifts
• Non-essential processes like reproduction and tissue repair are deprioritized

In the short term, this response is adaptive and helpful. The problem is that our modern lives trigger this same response repeatedly - not from predators, but from work deadlines, relationship conflict, financial worries, traffic, news, and the constant connectivity of our devices. Your body cannot tell the difference between a lion and a looming deadline.

Cortisol: The Double-Edged Hormone

Cortisol gets a bad reputation, but it is essential for life. In healthy amounts, cortisol:

• Helps regulate blood sugar
• Reduces inflammation
• Assists with memory formation
• Supports healthy metabolism
• Helps you wake up in the morning (cortisol naturally peaks upon waking)

The issue is not cortisol itself - it is chronic cortisol elevation. When stress is constant and your cortisol stays elevated day after day, the effects accumulate:

Digestive disruption. Cortisol suppresses digestive function. Chronic stress can lead to reduced stomach acid, slower gut motility, and altered gut bacteria - contributing to bloating, reflux, constipation, or irritable bowel symptoms. The gut-brain connection runs both ways: stress affects your gut, and gut problems can perpetuate stress.

Sleep disturbance. Cortisol should naturally drop in the evening to allow melatonin to rise and sleep to come. When cortisol stays elevated, you may feel wired at bedtime, have trouble falling asleep, or wake in the early morning hours. Poor sleep then increases cortisol further, creating a vicious cycle.

Weight changes. Cortisol promotes fat storage, particularly around the midsection. It also increases appetite and cravings for high-calorie foods - your body thinks it needs energy to deal with the ongoing threat. This is why chronic stress often leads to weight gain that proves resistant to diet and exercise.

Immune suppression. While acute stress can temporarily boost certain immune functions, chronic stress suppresses immunity. You may notice getting sick more often, taking longer to recover, or having wounds that heal slowly.

Hormonal imbalance. Cortisol production shares raw materials with other hormones, including sex hormones. When your body prioritises cortisol production, it can affect oestrogen, progesterone, and testosterone levels. This contributes to symptoms like irregular periods, PMS, low libido, and fertility challenges.

Brain function. Chronic cortisol elevation affects the hippocampus, the brain region involved in memory and learning. This contributes to brain fog, difficulty concentrating, and memory problems. Over time, it may even contribute to brain shrinkage.

Mood changes. Cortisol affects neurotransmitter balance, contributing to anxiety, irritability, and depression. The constant state of low-level alarm wears on you emotionally.

The Progression: From Acute to Chronic to Depleted

How stress affects you depends partly on how long it has been going on:

Acute stress produces a clear cortisol spike that resolves once the stressor passes. You feel the effects but recover relatively quickly.

Chronic stress keeps cortisol elevated for extended periods. Your body adapts somewhat, but the effects accumulate. This is where many health problems begin to develop.

Prolonged chronic stress can eventually lead to what some call "adrenal fatigue" - though the more accurate term is HPA axis dysregulation. After months or years of overproduction, your stress response system becomes dysregulated. Cortisol patterns flatten or invert, and you may feel exhausted but wired, unable to mount an appropriate stress response when needed.

Recognizing When Stress Is Affecting Your Health

Stress-related symptoms can be subtle at first and easy to attribute to other causes:

• Difficulty waking or fatigue despite adequate sleep
• Energy crashes in the afternoon
• Feeling wired but tired
• Difficulty relaxing or constant underlying tension
• Digestive symptoms that worsen with stress
• Getting sick frequently
• Weight gain around the midsection
• Brain fog, poor memory, or difficulty concentrating
• Anxiety or feeling on edge
• Difficulty falling or staying asleep
• Low libido
• Cravings for salt, sugar, or caffeine

If several of these resonate, your stress response system may need support.

Addressing Stress at the Root

Managing stress is not about eliminating all stressors - that is neither possible nor desirable. Some stress is healthy and helps us grow. The goal is building a system that can respond appropriately to stress and recover afterward, rather than staying perpetually activated.

Address what you can. Some stressors can be reduced or eliminated. This might mean setting boundaries, delegating, changing jobs, ending toxic relationships, or reducing commitments. Not everything is within your control, but some things are.

Change your perception. How you interpret situations affects your stress response. A deadline can feel like a threat or a challenge. Reframing stressors, practising perspective-taking, and building resilience through mindset work can genuinely reduce the physiological impact of stress.

Activate your relaxation response. Your parasympathetic nervous system (rest-and-digest) is the counterbalance to your stress response. Deliberately activating it helps regulate cortisol:

• Deep, slow breathing with extended exhales
• Meditation and mindfulness practises
• Gentle movement like yoga or walking
• Time in nature
• Warm baths
• Massage or self-massage
• Connection with loved ones
• Activities that bring genuine joy

Support your body physiologically. Certain nutrients are depleted by stress and support healthy cortisol regulation: magnesium, B vitamins, vitamin C, and omega-3 fatty acids. Adaptogenic herbs like ashwagandha, rhodiola, and holy basil have traditional use for supporting the stress response, though individual responses vary.

Prioritize sleep. Sleep deprivation is itself a stressor. Protecting your sleep - even when there is more to do - helps regulate cortisol and builds resilience.

Move your body. Regular moderate exercise helps regulate the stress response. Intense exercise, however, can be an additional stressor if overdone. Find the balance that leaves you energised rather than depleted.

The Bigger Picture

Stress is not separate from the rest of your health - it is woven through everything. Chronic stress contributes to gut problems, hormonal imbalances, immune dysfunction, weight issues, and mood disorders. Conversely, poor gut health, nutrient deficiencies, and inflammation can make you more susceptible to stress.

This interconnection is why addressing stress often has ripple effects across multiple symptoms. It is also why stress management deserves to be treated as seriously as diet and exercise in any health improvement plan.

Your nervous system learned its current patterns, and it can learn new ones. With consistent practise, you can shift from a body stuck in stress mode to one that responds appropriately and recovers fully. This shift affects not just how you feel emotionally, but your physical health at every level.

Want to explore the body systems most affected by stress? Learn about the gut-brain connection, understand inflammation's role in health, or explore nervous system regulation.