Updated: Jan 15
What is cortisol?
Often referred to as the primary stress hormone, cortisol is a hormone with an integral role in the relationship between the brain and body, and its response to stress. Cortisol is a glucocorticoid, or steroid hormone, giving it different biological properties than most other hormones which are derived from protein. Cortisol is made in the body from cholesterol, and is a primary product of the Hypothalamic-Pituitary-Axis (HPA Axis) aka the body’s main stress response system.
Where is it produced?
Cortisol is made by your adrenal glands or the two little triangular-shaped glands that sit atop each one of your kidneys. Though small in size, these glands are multifactorial, helping adrenal to regulate your body’s immune system, energy, sex drive, hormone cycles, fertility, reproduction, fat storage and blood sugar regulation. The adrenal glands are composed of an inner medulla and outer cortex. The cortex is further divided into three zones, with the zona fasciculata being the center of cortisol production. The adrenal glands are also responsible for the production of our DHEA, aldosterone, adrenaline, and noradrenaline.
What’s the function/role of cortisol?
Contrary to popular belief, cortisol is not inherently negative. The body relies on cortisol for a number of normal physiological processes, most of which act in order to protect you. By nature, cortisol is more prominent in times of higher stress (fight or flight). However, it is also regularly produced and utilized by the body in the absence of stress.
Cortisol communicates with virtually all bodily systems. As a result, it can indirectly influence both mental and physical health. Understanding your personal cortisol levels helps you navigate overall wellness, not just simply your response to stress.
The main functions of cortisol:
Blood pressure regulation
Bone density maintenance
Raising blood sugar
Influences memory formation
Influences insulin sensitivity
Influences adipose (fat) distribution
Influences energy levels
Indirectly impacts digestion
Cortisol follows a diurnal cycle, meaning it has natural peaks and valleys throughout a 24-hour cycle. Under normal circumstances, cortisol should be highest in the morning, decline throughout the day, and reach its lowest point as you get ready for bed. An important attribute of the hormone is known as the cortisol awakening response, or CAR, in which cortisol levels surge in the first 30-45 minutes of the day. This elevation is actually a good indication that you’re producing and utilizing proper amounts of cortisol throughout the day. This peak at the beginning of the day signals the body to prepare to function for the day. A good CAR will stimulate alertness and prepare you to feel awake and ready for the day; whereas a flat CAR may be indicative of fatigue, morning grogginess, and an overall lack in motivation for the day.
Now that I’ve provided a bit of context on how cortisol is certainly much more than a basic stress hormone, it’s important to highlight why it’s often demonized. Like many things in functional medicine, you only run into complications with cortisol when levels are too high or too low, at the wrong times of day. Both are indicative of your response to stress (perceived or otherwise), but the levels give insight as to how long your body has been fighting for you.
Cortisol dysregulation is a common health implication in our modern society. It’s important to note, however, that there are actual conditions that have extremely high (Cushing’s disease) or low (Addison’s disease) levels of cortisol production due to biological discrepancies. These are much different than cortisol dysregulation, and should be medically supervised.
Interpreting your levels is imperative, as it can have a variety of meanings. Typically, we see a few different patterns of cortisol dysregulation. High cortisol, in the absence of the aforementioned diseases, are generally indicative of an acute response to stress. Your body is running at full speed, but hasn’t been maintaining that output for a long period of time. This is a more acute response and can usually be modified by lifestyle factors that support your nervous system. On the contrary, low cortisol generally means your adrenal glands have been overproducing cortisol for such an extended period of time, they can’t keep up with the demand. They’ve become tired and are starting to fade. This low cortisol picture can be further broken down into 4 stages of fatigue, the last being absolute exhaustion.
Stages of cortisol
Symptoms of high and low cortisol
High blood pressure
Low sex dive
Persistent abdominal belly fat
Lowered pain threshold
Second wind at night
Waking in the middle of the night
Inability to concentrate
Salt and sugar cravings
Afternoon energy crashes
Joint and muscle pain
Low blood pressure
Depression / low mood
Low blood sugar
Role in circadian rhythm
Your circadian rhythm is a regulated system that follows a 24 hour cycle. Influenced by a group of neurons in the hypothalamus of the brain called the suprachiasmatic nucleus (SCN), the circadian rhythm can be considered your body’s internal clock. The SCN sits on the nerves of the eyes, responding to light.
Your circadian rhythm, being an internal clock, is responsible for initiating sleep and wake cycles by interpreting internal and external information. Your circadian rhythm impacts a number of biological functions, such as hormone release, digestion, hunger, body temperature, and tiredness.
Remember how we talked about cortisol’s diurnal pattern? Well, because of its peak in the morning, and fall as the day progresses, it follows a similar pattern (and can directly impact) your circadian rhythm. Inappropriate cortisol levels can negatively impact this rhythm, having a downstream effect on sleep and health disturbances.
5 ways to regulate your circadian rhythm
Cultivate a consistent schedule- wake up and go to bed at the same time daily.
Initiate light exposure upon waking (preferably from the sun) for ~20 minutes.
Time your caffeine- Cease caffeine intake within 8-10 hours of sleep time
Remember the basics- nutrition, movement, stress management
Test your cortisol levels
Root causes of cortisol imbalances
In times of immediate and acute danger, the body prepares to fight the danger or run from the danger (pump out cortisol quickly as a protective measure). If we’re using the typical analogy, our ancestors would be preparing to fight or flee from a threat. The blood and energy would rush from the organ systems that did not need to be optimally functioning in that moment of impending doom to their extremities to save their lives. This means shunting energy away from the organ systems involved in digestion, immune system, reproduction, urination and bowel movements. Over the many years since, our development has not come far enough to differentiate life or death situations from minor, everyday stressful situations. Meaning, a lion in the wild and your angry boss are still interpreted in a similar fashion. If inadequately managed, daily stressors of sitting in traffic, fear of being late, confrontations with your family, having marital troubles can all trigger this primal fight or flight response and cortisol imbalances.
Elevated cortisol can reduce the entire HPA Axis by raising thyroid binding globulin, ultimately reducing the free thyroid hormone available to your cells. This further reduces the conversion of your thyroid hormones, T4 to T3, and increases the conversion of T4 to reverse T3 (more on that here). Meaning, elevated cortisol slows (or stops) your ability to effectively produce and utilize thyroid hormones, potentially causing hypothyroid issues if unattended to. Remember, high cortisol means your body is on high alert; producing hormones takes a second seat to keeping you alive.
When the body isn’t given adequate calories to create energy from, it reverts to the way it knows can get the job done- cortisol production. Cortisol, though meant to only be at high levels for an acute amount of time, allows the body to continue to function. At a cost, through, as cortisol production eventually slows and leaves the body in a state of exhaustion. Supplying the body with adequate nutrients is the best way to negate the potential consequences here.
Moral of the story, cortisol often gets a bad rap. Yes, it is your primary stress hormone, but it’s an extremely necessary one. You need your body to be able to react and adapt to acute stress responses (cue a boss yelling at you, a fight with your spouse, or a close call with a bear in the woods). It only becomes an issue if it negatively impacts further biological function by being continuously under or over produced.
Katie Morra MS, RD, LDN, IFMCP is an Institute for Functional Medicine Certified Practitioner and Registered Dietitian Nutritionist specializing in gut and hormone optimization. Katie runs a fully virtual functional medicine practice, Gut Honest Truth, based out of Maryland. Katie focuses on the root causes of inflammation, autoimmune disease, irritable bowel syndrome, food sensitivities, hypothyroidism, hormone imbalance, adrenal dysfunction as well as other chronic disease states.