What is Cortisol's Function?

Have you ever wondered why you feel energized in the morning and ready to wind down at night? The answer lies in large part with a hormone called cortisol.

But, before we dig into cortisol, it’s worth understanding a bit more about how your body works. Get your pencils out, there will be a quiz at the end.

Note: there won’t be a quiz.)

Hormones are basically chemical messengers within your body. They help with various critical tasks like growth, development, metabolism, your sexual function and reproductive organs.

Cortisol specifically belongs to a class of “steroid” hormones called glucocorticoids. Other glucocorticoids are cortisone, prednisone, prednisolone, dexamethasone, betamethasone, and triamcinolone. It basically sounds like there’s a complete pharmacy operating in your body … which makes sense, right? We take medicine, either synthetic or natural, because its designed to trigger reactions within your body one way or another. So there must be things that are reacting!

Glucocorticoids have widespread effects on various organs and tissues in the body. Among many other things, they regulate metabolism, have powerful anti-inflammatory and immunosuppressive effects and play a vital role in the body's stress response, temporarily suppressing non-essential functions like immune response and digestion to prioritize energy allocation.

And that last role, the stress response, is specifically where cortisol plays a big role.

Cortisol, Stress and the Sleep-Wake Cycle

Kinda sounds like the lion, the witch and the wardrobe? While the tale of a hormone navigating your body and day isn’t quite as fantastic, it plays a bigger role in our day to day life. For those of us who don’t spend our days focused on Narnia at least.

Cortisol is produced by the adrenal glands atop your kidneys, serves as a powerhouse hormone with its primary function is to mobilize energy stores, enhance metabolism, and aid in the body's stress response. Feeling that fight or flight type of way? That’s cortisol doing its job.

When a lot of cortisol is released the feeling one gets is something anyone with heightened levels of anxiety is surely aware of. A heightened sense of alertness, but difficulty to concentrate on any one specific thing.

A heart that begins to thump a bit faster and blood that begins to rush. Cortisol stimulates the release of adrenaline, which can lead to an increase in heart rate and blood pressure. This response is part of the body's preparation for a "fight-or-flight" situation.

The dreaded jitters? Those are a result of cortisol breaking down glycogen into glucose and stimulating gluconeogenesis, leading to increased blood sugar levels. This can result in feelings of jitteriness or shakiness and potentially a craving for food or total loss of appetite.

Add it all up and it creates a heightened anxiety, irritability, or just an overall overwhelmed feeling. 

But it’s not cortisol’s fault! It’s just responding to circumstances. When it feels like things have begun to get tough for the body, it just kicks into protection mode … unfortunately it cannot tell that protection is not required from your fourth coffee of the day.

And that brings us to another critical aspect of your life under cortisol’s influence: the sleep-wake cycle. 

Cortisol’s Daily Cycle

Cortisol levels follow a daily pattern known as the circadian rhythm. In the morning, cortisol levels are at their highest, promoting wakefulness and providing the necessary energy to kickstart your day. As the day progresses, cortisol levels gradually decrease, facilitating sleep onset. This intricate dance between cortisol and your internal clock helps regulate your sleep patterns.

But add way too much caffeine or way too much stress and your levels will no longer be … level. High cortisol levels at 9 PM are not a recipe for a successful night’s sleep. The natural pattern of your day should result in low cortisol levels at the end of the night, right as your melatonin levels begin to rise. Melatonin helps signal the body that it’s time to sleep, until cortisol levels begin to peak again about 30 to 45 minutes after you wake up the next morning.

While cortisol is vital for normal bodily functions, chronically high levels of cortisol due to prolonged stress or certain medical conditions can have adverse effects on health. 

Excessive cortisol has been associated with impaired immune function, increased risk of infections, elevated blood pressure, weight gain, muscle weakness, and mood disturbances. Therefore, maintaining a balanced stress response and effectively managing stress are crucial for overall well-being.