Understanding Cortisol: The Body’s Stress Hormone

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If you've ever felt your heart race during a stressful work meeting or woken up with a jolt of energy ready to seize the day, you have the hormone cortisol to thank. Cortisol is an important steroid hormone that helps regulate many essential functions in the body. Getting familiar with what cortisol is, what it does, and how to keep your levels balanced can give you key insights into managing your health and well-being.

Cortisol 101

First, what is cortisol exactly? On a chemical level, cortisol is classified as a glucocorticoid - a type of steroid hormone. Steroid hormones like cortisol are made from cholesterol and have a similar molecular structure. Your adrenal glands sit above your kidneys and are responsible for producing and secreting cortisol.

When triggered by physical or psychological stress, the hypothalamus region of the brain signals the pituitary gland to release adrenocorticotropic hormone (ACTH). ACTH then stimulates the adrenal glands to produce more cortisol and release it into the bloodstream. From there, cortisol carries out its various regulatory effects on metabolism, immunity, blood pressure, and more.

Cortisol performs several key functions in the body

As a crucial hormone, cortisol impacts many important processes and systems throughout the body:

  • Regulates metabolism - Cortisol increases glucose production to give cells readily available energy. It also mobilizes amino acids from muscle, breaks down fat, and moderates insulin secretion.
  • Manages immune response - Cortisol helps control inflammation levels and the activity of different immune cells. However, chronically elevated cortisol can suppress the immune system.
  • Influences cardiovascular function - Cortisol varies blood pressure and heart rate as needed for fight-or-flight response. But prolonged high cortisol may damage blood vessels and raise risk of heart disease.
  • Impacts bone health - Cortisol regulates bone turnover and calcium absorption from the intestines. However, excess cortisol weakens bones over time by inhibiting bone formation.
  • Affects mood and motivation - Cortisol boosts alertness, memory, and motivation when needed. But chronic stress and high cortisol can negatively impact mood, emotions, and fear response.

So, in moderation, cortisol provides vital metabolic and immune support. But when you have high or low cortisol level for too long, it can undermine health in multiple ways.

Cortisol production follows a daily circadian rhythm

Cortisol secretion fluctuates in a daily pattern known as a circadian rhythm. Levels are highest in the early morning, around 6:00-8:00am to give you a boost of energy to start the day. Your high cortisol level gradually declines throughout the day, reaching lower cortisol levels in the evening around midnight.

This circadian cortisol cycle helps regulate sleep-wake patterns and prime the body with alertness when needed. High cortisol level spikes also occur after intense exercise or in response to sudden stressors like important meetings or confrontations. These short-term spikes adaptively provide your body and mind with extra resources to manage challenging situations.

However, when cortisol rhythms become dysregulated due to chronic stress or lifestyle factors, it can lead to a host of adverse health effects.

Both high and low cortisol levels can negatively impact health

If cortisol levels remain too high or low for prolonged periods of time, it can impact well-being in various ways:

Effects of elevated cortisol

  • Increased blood glucose - raises diabetes risk
  • High blood pressure - increases risk of heart attack and stroke
  • Lowered immunity - more susceptible to infections
  • Loss of bone mineral density - leads to osteoporosis over time
  • Impaired memory and mood - can worsen anxiety and depression
  • Weight gain - especially increased belly fat

Conditions associated with a low cortisol level

  • Adrenal insufficiency or Addison's disease
  • Pituitary disorders
  • Long-term use of steroid medications
  • Severe stress, surgery, or septic shock

What causes low cortisol levels?

Some people deal with low cortisol levels, and understanding what's behind it is the first step to getting your levels back on track. Low cortisol is usually caused by an issue in one of two places - the pituitary gland or the adrenal glands. While we are a company of doctors and medical experts, we’re not YOUR doctor, so do not take any of this as a diagnosis for you, but rather a guide to get curious and form questions for your doctors and medical support team.

Primary adrenal insufficiency 

When the adrenal glands themselves are damaged, it's known as primary adrenal insufficiency or Addison's disease. Symptoms like weakness and fatigue can creep up, and if low cortisol goes untreated for too long, it can become really serious.

With Addison's, cortisol levels dip too low, along with another hormone called aldosterone.

Often Addison's is the result of an autoimmune disorder damaging the adrenal glands. For some folks, infections like TB can also be a cause - though treatment advances have made this less common nowadays. Those with weakened immune systems from HIV/AIDS face higher Addison's risk too.

Other potential reasons for Addison's include:

  • Cancer cells in the adrenals
  • Surgery removing the glands
  • Bleeding into the glands
  • Genetic conditions impacting adrenal function
  • Certain antifungal meds
  • The anesthesia drug etomidate

Addison's symptoms tend to creep up slowly at first. An illness or injury can suddenly make them more obvious since the body is under more stress. These include:

  • Extreme tiredness
  • Weight loss
  • Low appetite
  • Darkened skin
  • Low blood pressure
  • Fainting spells
  • Salt cravings
  • Nausea
  • Diarrhea
  • Vomiting
  • Abdominal discomfort
  • Muscle/joint aches
  • Irritability
  • Depression
  • Hair loss or sexual dysfunction in women
  • Irregular periods in women

Diagnosing Addison's means getting to the root of those insufficient cortisol levels. With treatment and self-care, living with Addison's is manageable for most. We're here to support you however we can on your path to well-being.

Secondary adrenal insufficiency

On the other hand, secondary adrenal insufficiency happens when there's a problem with the pituitary gland properly telling the adrenal glands to release cortisol. This is still a medical issue that needs attention, but catching it early and making lifestyle changes can help manage those low levels.

Secondary adrenal insufficiency is the more common type and stems from the pituitary gland. The pituitary is supposed to release a hormone called ACTH that tells the adrenal glands to produce cortisol. When pituitary function falters, not enough ACTH gets made, and cortisol levels drop as a result.

There are several reasons your pituitary might not be releasing enough ACTH:

  • An autoimmune disorder disrupting normal function
  • Tumors or infections in the pituitary
  • Bleeding into the gland
  • Genetic conditions impacting development
  • Pituitary removal surgery for other treatments
  • Traumatic brain injury

When the communication breaks down between the pituitary and adrenal glands, it leaves you with insufficient cortisol even though your adrenals may be intact. Identifying where along the HPA axis the signals are getting crossed is key. With proper treatment to address the underlying cause, cortisol levels can often be restored.

We know how frustrating and debilitating hormone issues can be. At Apollo Neuro, we're always here to support you on your path to wellness, whether through our products or other resources. Your health matters to us.

Several other potential causes of chronically low cortisol production can include:

  • Steroid medications - Long-term use of steroid drugs like prednisone can suppress natural cortisol production.
  • Severe illness or trauma - Critical health events like septic shock, surgery, or burns can disrupt cortisol rhythms.
  • Chronic stress - Paradoxically, although acute stress raises cortisol, chronically high stress can blunt the cortisol response over time.
  • Aging - Cortisol production can decrease gradually with age due to wear and tear on the hypothalamic-pituitary-adrenal axis.

Symptoms of low cortisol include fatigue, nausea, low blood pressure, and cravings for salty foods. Untreated adrenal insufficiency can lead to an adrenal crisis which requires emergency medical care.

Diagnosing the underlying cause through lab tests allows proper treatment to restore normal cortisol levels when possible.

What causes high cortisol levels?

In discussing low cortisol levels, it’s also important to touch on high cortisol levels. There are several factors that can contribute to abnormally elevated cortisol production:

  • Chronic stress - Prolonged physical or psychological stress keeps cortisol levels persistently high. This includes occupational stress, financial hardship, traumatic life events, etc.

  • Hormone disorders - Diseases like Cushing's syndrome and adrenal tumors cause excess cortisol secretion.

  • Medications - Steroid medications used to treat conditions like asthma and rheumatoid arthritis can increase cortisol.

  • Obesity - Increased cortisol breakdown in fatty tissue, as well as hormones and inflammation associated with obesity, can sustain high levels.

  • Depression - The stress hormone and neurotransmitter imbalances seen in depression frequently involve elevated cortisol and stress.

  • Insulin resistance - Conditions like metabolic syndrome and type 2 diabetes that are marked by insulin resistance tend to also have high cortisol levels.

Identifying and addressing the reasons for cortisol excess allows for better regulation of its production and secretion if you want to learn how to lower cortisol.

Ways to balance cortisol levels through lifestyle

  • Get enough sleep - allow for cortisol rhythms to follow natural cycles as cortisol and sleep are closely linked
  • Exercise - reduces cortisol response to stress
  • Relaxation techniques - lower cortisol secretion from chronic stress
  • Healthy nutrition - supply micronutrients needed for cortisol regulation
  • Consider supplementation - adaptogens like ashwagandha help moderate cortisol

Among lifestyle changes for maintaining healthy cortisol, using technologies like Apollo Neuro's wearable device, called the Apollo wearable, helps support desired health goals. 

Apollo's gentle vibrations, called Apollo Vibes, are designed to improve resilience, sleep, focus and more. Vibes like Focus, Sleep, and Energy can help get you where you want to be. Energy provides a calming alertness to start your day, while Unwind and Calm Vibes help counter elevated cortisol from stress. 

Using Apollo's Sleep Vibes and Unwind Vibes before bed supports your natural overnight cortisol dip. Optimizing your cortisol rhythms with Apollo's precisely engineered vibrations can enhance your body's natural stress adaptation for both mental and physical wellbeing. As with any wellness tool, the Apollo wearable aims to complement expert guidance in caring for your unique health needs.

Key takeaways on cortisol and its importance for health

Cortisol plays a crucial role in regulating metabolism, immunity, blood pressure, bone health, and mental state. Although essential for energy, stress response, and controlling inflammation, both elevated and insufficient cortisol levels can negatively impact wellbeing in various ways. Paying attention to lifestyle factors that influence cortisol - like sleep, exercise, nutrition and stress management - can help maintain a healthy cortisol balance and its many benefits for overall health.


1.Thau, Lauren, et al. “Physiology, Cortisol.”, StatPearls Publishing, 29 Aug. 2022, Accessed 12 Sept. 2023

2. “Addison’s Disease - Symptoms and Causes.” Mayo Clinic, 2022, Accessed 12 Sept. 2023.‌

3. “Corticotrophin-Releasing Hormone | You and Your Hormones from the Society for Endocrinology.”, 2020, Accessed 12 Sept. 2023.

4.. and, Diabetes. “Symptoms & Causes of Adrenal Insufficiency & Addison’s Disease.” National Institute of Diabetes and Digestive and Kidney Diseases, NIDDK - National Institute of Diabetes and Digestive and Kidney Diseases, 12 Sept. 2023, Accessed 12 Sept. 2023.