As everyone knows all too well, sleep is essential to keep your mind and body functioning at their very best. But there are things that can take place externally and internally that can affect the quality of your sleep.
One of these factors is the hormone cortisol, which can have a surprisingly large impact on your ability to get a good night’s sleep.
Below, we explain everything you need to know about cortisol and its link to sleep so you can start snoozing more soundly in no time.
What is cortisol?
“Cortisol is known as the stress hormone,” explains Lulu Guo, MD, of Arizona’s Valley Sleep Center. “Cortisol increases sugars in the bloodstream and enhances the brain’s use of glucose.”
It also increases the availability of substances that repair tissues, adds Guo. “Because cortisol is an essential hormone, it affects almost every organ and tissue in the body,” she says.
Cortisol is also commonly known as the hormone that drives one’s fight or flight response. And it can even come into play with illnesses.
“Perhaps one of the most important functions of cortisol is regulating the body’s stress response, which is key when it comes to managing chronic illness,” says Guo.
How does cortisol work?
Cortisol is produced in the adrenal glands as well as in the hypothalamus and pituitary gland in your brain, and it really does impact most everything in the human body.
As part of a complex system known as the hypothalamic-pituitary axis (HPA), which combines part of your central nervous system and endocrine system, cortisol even extends to your sleep-wake cycle.
Melatonin is another hormone produced in this system. Melatonin is the hormone released by the brain’s pineal gland when it gets dark outside.
Cortisol and melatonin work together within the HPA axis to regulate your sleep-wake cycle.
“While cortisol is the main product of the HPA axis, melatonin has a regulating effect on the HPA axis,” says Guo.
Both hormones need to work together harmoniously to achieve good-quality sleep.
What factors contribute to cortisol production?
There are several influences that can contribute to cortisol production, but one trumps them all.
“Stress is number one,” says Lauri Leadley, president and founder of Valley Sleep Center. “Stress causes both behavioral and physical illnesses.”
Work and home life dysfunction, addiction, mental health disorders, chronic pain, and more can be the basis for stress, she explains.
Leadley adds that other factors can include pituitary gland issues, which can cause headaches, vision problems, severe cases of nausea, vomiting, fatigue, and sexual dysfunction.
“Sometimes, adrenal gland tumors or cysts can negatively impact cortisol production, while other factors include medication side effects or hormone imbalance having to do with estrogen levels,” she says.
Addison’s Disease, a condition in which the adrenal glands don’t produce enough hormones, can lower cortisol levels too much. On the flip side, Cushing’s Syndrome produces too much cortisol.
Leadley says that perhaps the biggest factor besides stress is untreated obstructive sleep apnea, “which significantly increases 24-hour cortisol levels and can have detrimental health effects long-term.”
Lastly, diet is something that can influence cortisol production. Specifically, a diet that’s marked by high amounts of refined sugar, salt, animal-derived proteins and fats, and low intakes of fruit and vegetables can raise cortisol levels, according to one 2016 study.
What’s the link between sleep and cortisol?
Cortisol levels and sleep have a bidirectional relationship. High levels of cortisol can lead to poor sleep, while poor sleep can increase cortisol levels.
Your sleep-wake cycle follows a circadian rhythm, which is synchronized with nighttime and daytime.
Cortisol production also follows a similar circadian rhythm. Cortisol production drops to its lowest level around midnight and peaks an hour after you wake up.
“If cortisol is at the appropriate levels and the body is functioning with no underlying conditions, cortisol and sleep can play harmoniously together,” says Leadley. “Cortisol will contribute to your morning awakening, which makes you feel refreshed and motivated to firmly plant your feet on the floor and move through the day.”
When cortisol is off though, attaining the cyclical rhythm of life is difficult, adds Leadley.
There are also some smaller amounts of cortisol released throughout the day and night, corresponding to shifts in your sleep cycles.
Studies show that when your HPA is overly active, it can disrupt your sleep cycles, leading to insomnia, shortened sleep time, and fragmented sleep.
Studies also find that insomnia can lead to increased cortisol production during the day, hence the bidirectional relationship between cortisol and sleep.
What are the symptoms of high cortisol levels?
In addition to there being a connection between cortisol levels and sleep problems, high levels of cortisol can cause other health consequences, including inflammation, anxiety, depression, memory problems, headaches, and heart disease.
“We often see weight gain as a top symptom,” adds Guo. “Others experience acne, thinning hair, easy bruising, muscle weakness, and slowed healing.”
Can high cortisol levels cause insomnia?
Research shows high cortisol can lead to trouble sleeping, and vice versa. But Guo says the link between a lack of sleep and cortisol can get a bit murky, noting that it’s “unclear” whether high cortisol is a cause, consequence, or both.
What causes high cortisol at night?
Since cortisol is the stress hormone, if it’s raised at night due to daytime stress, a health condition, or another factor, the stress response can cause your body to wake up. Low, yet balanced, cortisol levels at night are the key to a good night’s sleep.
How do you lower your cortisol levels so you can sleep?
There are some ways you can lower cortisol levels and improve your sleep. While it’s best to chat with your doctor if you’re having trouble sleeping (and if lifestyle changes aren’t helping), you can certainly try to:
- Practice meditation
- Do deep breathing
- Exercise regularly
- Change your diet
- Go to therapy
- Take medication
Having trouble sleeping? We put together this list of things you can do if you can’t sleep to help you get your shuteye back on track.