Insomnia And Cortisol: Does “Fixing Cortisol” Help Insomnia?
Quick Summary
While people with chronic insomnia do have moderately higher average cortisol levels, this link doesn't prove that cortisol is the cause of the sleep problem - it could be the reverse.
Effectively treating insomnia with proven methods like Cognitive Behavioral Therapy for Insomnia (CBT-I) does not reliably or predictably lower cortisol levels, suggesting cortisol isn't the primary lever for improving sleep in insomnia.
There are no clinical trials that show directly lowering cortisol with supplements or special protocols resolves insomnia.
The one cortisol pattern that does seem to predict future insomnia risk is a blunted (weaker) response to stress, not the chronically high levels often blamed for the condition.
Is High Cortisol Causing Your Insomnia? What the Science Actually Says
Many people believe that high cortisol, often called the body's main "stress hormone," is the direct cause of their insomnia. We hear this in the clinic from time to time. And a quick search online reveals a sprawling wellness industry built on this idea, offering everything from "adrenal support" supplements to "cortisol detox" diets, all promising to calm an overactive stress system and restore natural sleep.
The story is appealing because it feels right. Insomnia is stressful, and cortisol is linked to stress, so it seems logical that one must be causing the other. This narrative offers a simple, tangible villain - a single hormone that can be measured with a home test and supposedly "fixed" with the right product. It presents an easier path than the more involved work of changing the habits, thoughts, and behaviors that truly maintain a sleep problem.
But while it’s true that cortisol is involved in the body’s stress response, the popular claim that you can fix insomnia by "fixing your cortisol" deserves a closer look.
Is there solid evidence to support this connection, or has a small scientific finding been stretched too far?
To find out, we need to ask a few specific questions.
First, is there a real, measurable difference in cortisol levels between people with insomnia and those who sleep well?
Is Cortisol Really Higher in People with Insomnia?
Yes, on average, people with chronic insomnia have moderately higher cortisol levels than good sleepers. This observation is supported by scientific research. The most comprehensive evidence comes from a 2022 meta-analysis, a type of study that pools the results of many previous studies to get a more reliable overview. This analysis combined the data from 20 different studies and found that people with chronic insomnia did indeed have elevated cortisol, especially when measured in the blood (Dressle et al., 2022).
This finding builds on earlier, more detailed research. One notable study measured cortisol levels every 20 minutes over a full 24-hour period. It found that individuals with insomnia had consistently higher levels of both cortisol and adrenocorticotropic hormone (ACTH), the chemical signal from the brain that tells the adrenal glands to release cortisol. The difference was most pronounced in the evening and the first half of the night, exactly when you’d want those levels to be low (Vgontzas et al., 2001).
These studies are looking at the activity of the hypothalamic-pituitary-adrenal (HPA) axis, the body’s central command network for managing stress. It seems that in people with insomnia, this entire system runs at a slightly higher setting.
However, the details matter. The difference isn't as simple or dramatic as the online narrative suggests. The 2022 meta-analysis noted that the results across the 20 studies were quite varied; some found a clear difference in cortisol, while others found none at all.
The effect was also much stronger in people whose sleep was objectively disturbed, as measured by polysomnography, a comprehensive in-lab sleep study that tracks brain waves, breathing, and muscle activity. In contrast, the link was weaker for people whose main complaint was the subjective feeling of poor sleep without objective confirmation.
This detail is important. It suggests that higher cortisol is more closely linked to how physically severe the sleep disruption is rather than just an insomnia diagnosis itself. So, while the finding is real, it's moderate and not uniform across everyone with insomnia.
This leads to the most important question of all: does a moderate increase in cortisol actually cause the sleeplessness, or is it just a side effect?
Does High Cortisol Cause Insomnia?
No, a higher cortisol level in people with insomnia does not automatically mean it is the cause. This is where the popular story often makes a critical mistake, confusing a correlation, two things happening at the same time, with causation, where one thing directly causes the other. The studies showing higher cortisol are case-control studies, meaning they compare a group with a condition (insomnia) to a group without it. This type of study can only show that a difference exists; it can't tell us which came first or what is driving the change.
There are several possibilities:
High cortisol could be a cause of insomnia.
High cortisol could be a result of fragmented sleep and the stress it causes.
Both high cortisol and insomnia could be caused by a third, underlying factor.
Think of it like the temperature gauge in your car. If you're driving up a long, steep hill, the engine works harder, and the temperature gauge rises. The reading on the gauge is real and accurately reflects the strain on the engine. But if you were to simply reach over and manually turn the needle on the gauge back down, it wouldn't make the hill any less steep or cool down the engine. The gauge is an indicator, not the cause of the heat.
In the same way, we can't know from these studies whether cortisol is the engine driving insomnia or just the gauge reflecting the strain of sleeplessness. To figure that out, we need to see what happens when we actually fix the problem through a proven method.
So, what happens to cortisol when insomnia is treated effectively?
What Happens to Cortisol Levels When Insomnia Is Treated Effectively?
When insomnia is successfully treated, cortisol levels do not reliably or predictably return to normal. This finding is the most direct challenge to the "fix cortisol, fix insomnia" theory. If high cortisol were the direct cause, then successfully treating insomnia should consistently lower it, and the improvement in sleep should match the drop in cortisol. The research shows this isn't the case.
Scientists have tested this using Time In Bed Restriction Therapy, a core component of Cognitive Behavioral Therapy for Insomnia (CBT-I). This technique involves limiting a person's time in bed to only the hours they are actually sleeping, which helps make sleep more solid and continuous, reducing time spent awake and frustrated.
In one study, eleven people with severe insomnia underwent five weeks of this therapy. Their insomnia severity scores dropped dramatically, indicating a major improvement in their sleep. Yet, their cortisol levels did not fall. In fact, their early-morning cortisol levels actually rose after treatment (Miller et al., 2015).
A separate, smaller study used the same effective treatment and found the exact opposite pattern. As patients' sleep improved, their cortisol levels trended downward (Vallières et al., 2013).
The fact that two studies using the same effective treatment produced opposite results for cortisol is the key takeaway.
If cortisol were the central problem that needed fixing, you would expect it to behave the same way every time sleep improved. Instead, it seems to be an unreliable marker.
Sleep can get significantly better whether cortisol goes up, down, or stays the same. This strongly suggests that cortisol is not the primary lever that controls sleep in people with chronic insomnia.
This brings us to the other side of the coin. If treating insomnia doesn't depend on fixing cortisol, has anyone ever shown that deliberately lowering cortisol can fix insomnia?
Has Anyone Proven That Lowering Cortisol Cures Insomnia?
No, there is no clinical trial evidence showing that interventions designed to lower cortisol can resolve insomnia. Despite the many products and protocols marketed with this exact promise, the science to back it up is missing.
This issue was examined in a systematic review of a related popular concept called "adrenal fatigue." This is the idea that chronic stress wears out the adrenal glands, leading to symptoms like fatigue and poor sleep, which can supposedly be corrected by "supporting" the adrenals or manipulating cortisol output.
The researchers conducted an exhaustive search of all published scientific literature and found no consistent evidence that "adrenal fatigue" even exists as a medical condition. Furthermore, the studies that tried to test for it often produced inconsistent results, and none could link a "fix" in cortisol levels to a resolution of symptoms (Cadegiani & Kater, 2016).
This is directly relevant to the cortisol-insomnia debate. The very interventions that the popular narrative suggest, lowering high cortisol or boosting low cortisol, have not been shown to work for the conditions they claim to treat, including poor sleep.
When you put all the evidence together, the picture becomes clear. The treatment that reliably works for insomnia (CBT-I) doesn't depend on changing cortisol, and the treatments that claim to change cortisol have no evidence that they work for insomnia.
So, if chronically high cortisol isn't the cause, does that mean cortisol has no role at all in who develops insomnia?
Does an 'Abnormal' Cortisol Profile Predict Future Insomnia?
Yes, some people do have a cortisol pattern that predicts a higher risk of developing insomnia later in life - but it is the opposite of what most people assume. The research points not to an overactive stress response, but to a blunted one, meaning a stress system that under-reacts.
One study looked at people with a family history of insomnia. Researchers found that these at-risk individuals had an abnormally flat or blunted cortisol response when put through a standardized laboratory stress test. Their bodies didn't mount the same strong cortisol surge as people without a family history of insomnia.
Importantly, this pattern was present even in family members who had not yet developed insomnia themselves, suggesting it might be an early warning sign of risk (Drake et al., 2017). A more recent study confirmed this direction, finding that a blunted cortisol response to stress often precedes the onset of insomnia (Reffi et al., 2022).
This is a completely different story from the one told by the wellness industry. It suggests an inherited trait related to how the HPA axis responds to a challenge, not a simple case of having too much cortisol floating around day-to-day. This finding directly contradicts the idea that you need to lower your cortisol to sleep better. If anything, the scientific vulnerability marker points in the other direction.
This brings up a final, practical question: if it’s not about high cortisol, what is actually keeping people with chronic insomnia awake?
If It's Not Cortisol, What Is Actually Causing Chronic Insomnia?
For most people, chronic insomnia is driven by learned habits and thought patterns, not hormonal ones. After an initial trigger that starts the sleep problem (like a period of stress or illness), the insomnia problem is perpetuated by a set of learned behaviours, and thought patterns that support the behaviours. These then take on a life of their own.
At its core, chronic insomnia is often a mismatch between the amount of sleep your body is capable of getting and the amount of time you spend in bed trying to sleep. When you spend eight, nine, or even ten hours in bed believing you should sleep eight hours, but your body can currently only generate six hours of sleep, the sleep you do get becomes fragmented and light.
Over time, your brain starts to form a powerful learned association. The bed, which should be a cue for rest and relaxation, becomes a place associated with frustration, anxiety, and the mental effort of "trying" to sleep. Your nervous system goes on high alert as soon as your head hits the pillow, the mind racing. This state of mental and physical alertness is what fights off sleep, night after night, long after the original trigger for the insomnia is gone.
So, if you've been chasing a hormonal solution without success, where do you go from here?
Where To From Here?
If you have spent time and energy trying to "fix" your cortisol to cure your insomnia with little to show for it, please know that this is not a personal failure. It is the predictable result of pursuing a “wellness industry” explanation that the scientific evidence does not support as the primary driver of the problem.
Fortunately, chronic insomnia is a well-understood condition, and for most people, the factors that keep it going are identifiable and, most importantly, treatable.
Working with a Behavioral Sleep Medicine specialist (aka sleep psychologist) is very different from reading generic sleep hygiene tips or trying another sleep supplement. It involves a structured, personalized program that directly targets the habits and thought patterns that are actually maintaining your sleeplessness.
A specialist can help you identify the specific mismatch between your sleep ability and your time in bed, and guide you through evidence-based techniques to break the cycle of learned frustration and alertness in bed.
The goal is to rebuild a healthy, natural sleep pattern from the ground up.
If chasing your cortisol levels hasn't brought you relief, it isn't a sign that your sleep is broken beyond repair. It's a sign that it's time to focus on the strategies that have scientific evidence showing they work.
Frequently Asked Questions About Cortisol and Insomnia
Q1: Does high cortisol cause insomnia?
A1: High cortisol is not considered the direct cause of chronic insomnia. While there is a link between the two, studies show that successfully treating insomnia does not depend on lowering cortisol, which suggests it is not the primary driver of the condition (Miller et al., 2015; Vallières et al., 2013). The real drivers for most people are learned habits and thought patterns that create mental and physical alertness at night.
Q2: Do people with insomnia have higher cortisol levels?
A2: Yes, on average, people with chronic insomnia have moderately higher cortisol levels than people who sleep well. A large analysis of 20 different studies confirmed this link, especially when cortisol was measured in the blood (Dressle et al., 2022). However, this is just an average, and the effect is not uniform for everyone with insomnia.
Q3: Will lowering my cortisol with supplements fix my insomnia?
A3: There is no clinical trial evidence to suggest that lowering your cortisol levels will fix insomnia. A systematic review looking into the related concept of "adrenal fatigue" found no proof that interventions designed to alter cortisol levels resolve symptoms like poor sleep (Cadegiani & Kater, 2016). The treatments that are proven to work for insomnia, like Cognitive Behavioral Therapy for Insomnia (CBT-I), do not focus on changing cortisol levels.
Q4: Can a cortisol test tell me why I can't sleep?
A4: A cortisol test is unlikely to tell you why you have chronic insomnia. While tests might show elevated levels, this doesn't prove it's the cause of your sleep problems. Interestingly, scientific research has found that the one cortisol pattern that can predict future insomnia risk is a blunted or weaker-than-normal response to stress, not chronically high levels (Drake et al., 2017; Reffi et al., 2022).
Q5: If it's not cortisol, what is the most effective treatment for insomnia?
A5: The most effective treatment for chronic insomnia targets the learned habits and thought patterns that perpetuate the problem. This is typically done through a structured program like Cognitive Behavioral Therapy for Insomnia (CBT-I).
Q6: What is the HPA axis and how does it relate to insomnia?
A6: The HPA axis, which stands for the hypothalamic-pituitary-adrenal axis, is the body’s central command network for managing stress. Research shows that in people with chronic insomnia, this entire system tends to run at a slightly higher setting, leading to the moderately elevated cortisol levels observed in some studies (Vgontzas et al., 2001). However, this appears to be more of a symptom or a parallel issue rather than the root cause of sleeplessness.
References
Cadegiani, F. A., & Kater, C. E. (2016). Adrenal fatigue does not exist: A systematic review. BMC Endocrine Disorders, 16, 48
Drake, C. L., Cheng, P., Almeida, D. M., & Roth, T. (2017). Familial risk for insomnia is associated with abnormal cortisol response to stress.Sleep, 40(10), zsx143.
Dressle, R. J., Feige, B., Spiegelhalder, K., Schmucker, C., Benz, F., Mey, N. C., & Riemann, D. (2022). HPA axis activity in patients with chronic insomnia: A systematic review and meta-analysis of case-control studies. Sleep Medicine Reviews, 62, 101588.
Miller, C. B., Kyle, S. D., Gordon, C. J., Espie, C. A., Grunstein, R. R., Mullins, A. E., Postnova, S., & Bartlett, D. J. (2015). Physiological markers of arousal change with psychological treatment for insomnia: A preliminary investigation.PLoS ONE, 10(12), e0145317.
Reffi, A. N., Cheng, P., Kalmbach, D. A., Jovanovic, T., Norrholm, S. D., Roth, T., & Drake, C. L. (2022). Is a blunted cortisol response to stress a premorbid risk for insomnia? Psychoneuroendocrinology, 144, 105873
Vallières, A., Ceklic, T., Bastien, C. H., & Espie, C. A. (2013). A preliminary evaluation of the physiological mechanisms of action for sleep restriction therapy. Sleep Disorders, 2013, 726372.
Vgontzas, A. N., Bixler, E. O., Lin, H. M., Prolo, P., Mastorakos, G., Vela-Bueno, A., Kales, A., & Chrousos, G. P. (2001). Chronic insomnia is associated with nyctohemeral activation of the hypothalamic-pituitary-adrenal axis: Clinical implications. Journal of Clinical Endocrinology & Metabolism, 86(8), 3787–3794.
Written By Dan Ford, DBSM, Sleep Psychologist
Published By The Better Sleep Clinic
