Cortisol is widely known as a \u201cstress hormone.\u201d Some research suggests that it may impact blood sugar, proteins, cholesterol, and inflammatory markers. According to one hypothesis, imbalanced cortisol may create a lot of health issues that at first seem unrelated. What does the science say? Learn about factors that may trigger excessive cortisol release in this article.<\/p>\n
Disclaimer:<\/em><\/strong> This post focuses on the neuroscience of the stress response in relation to cortisol. It is solely informational. Talk to your healthcare provider if you feel like you\u2019re under too much stress or if your cortisol labs are abnormal. <\/em><\/p>\n Since the stress response pathway is so critical to our health, it’s important to explore what increases and what decreases it. Modern neuroscience has come a long way in understanding the stress response [R<\/a>].<\/p>\n According to one hypothesis, the problem comes when it’s activated too little, too much or it doesn’t have a good rhythm. In other words, HPA \u201cdysregulation\u201d is viewed as bad [R<\/a>].<\/p>\n Scientists point out that this has nothing to do with the capacity of the adrenal glands (See the myth of <\/a>adrenal fatigue<\/a>). Rather, it\u2019s likely related to many other factors. The consequences also seem to depend on whether the HPA axis is activated short- or long-term and to what extent [R<\/a>].<\/p>\n We know that the HPA axis controls such vital functions as heart rate<\/a>, blood pressure, and digestion (R<\/a>).<\/p>\n The HPA axis also communicates with several regions of the brain, including the limbic system, which is implicated in motivation<\/a> and mood, with the amygdala, which generates fear in response to danger, and with the hippocampus, which plays an important part in memory formation as well as in mood and motivation (R<\/a>).<\/p>\n In addition, the HPA axis is also connected with brain regions that control body temperature, suppress appetite, and control pain<\/a> (R<\/a>).<\/p>\n Research suggests that a chronically over-activated stress response may decrease growth, reproduction, metabolism, and immunity (R<\/a>).<\/p>\n Similarly, the HPA axis also interacts with various other glandular systems, among them those producing reproductive hormones, growth hormones, and thyroid hormones<\/a> (R<\/a>, R<\/a>).<\/p>\n Prolonged HPA activation is hypothesized to hinder the release of growth hormone<\/a> and IGF-1<\/a>, both of which are essential for normal growth. Cortisol also seems to cause tissues to be more resistant to IGF-1, according to animal data (R<\/a>).<\/p>\n Researchers suspect that psychological symptoms excessive HPA activation include sleep<\/a> disturbances, loss of libido, and loss of appetite, as well as an increased risk for accumulating abdominal fat. More human data are needed (R<\/a>, R<\/a>).<\/p>\n Additionally, it\u2019s a good idea to read our post on why stress is bad<\/a> for a more detailed look.<\/p>\n Note that the HPA axis is not the only system that participates in the stress response. Your sympathetic nervous system (SNS) is a different arm of the stress response. As an example, beta 2-adrenoreceptor blockers like propranolol block beta receptors in the heart that belong to the SNS (R<\/a>).<\/p>\n Sympathetic, fight-or-flight activity can also be counteracted by parasympathetic, rest-and-digest activity. This is part of the cholinergic pathway in the body<\/a>.<\/p>\n Lastly, the stress response can involve many other possible factors – including brain chemistry, environment, health status, and genetics – that may vary from one person to another.<\/p>\n Scientists think stressors that are uncontrollable, threaten physical integrity or involve trauma tend to have a high, flat cortisol release, with lower-than-normal levels of cortisol in the morning and higher-than-normal levels in the evening. This seems to result in a high overall level of daily cortisol release (R<\/a>).<\/p>\n On the other hand, controllable stressors tend to produce higher-than-normal morning cortisol (R<\/a>).<\/p>\n However, there\u2019s not enough reliable evidence to verify this cortisol release pattern. Large human studies are needed.<\/p>\n Here\u2019s a simple way to think about the circadian rhythm. The body has thousands of processes going on at any given moment. Many of these processes function better in concert with other processes – just like in a symphony, where different sounds work better with other sounds.<\/p>\n These processes have a certain rhythm or flow. Scientists suggest that the body conducts this orchestra with \u201cclock genes.\u201d When they get expressed, it happens all over the body, in a synchronous way (R<\/a>).<\/p>\n Circadian rhythm disruptions have been linked with inflammation, oxidative stress<\/a>, and cognitive problems (R<\/a>).<\/p>\n Since the HPA axis (includes CRH, ACTH, Cortisol) is involved in so many bodily functions, science emphasizes the importance of its rhythm.<\/p>\n In humans, cortisol levels seem to peak in the early morning (approximately 8 a.m.) and reach their lowest level at about midnight-4 a.m., or three to five hours after the onset of sleep. Information about the light\/dark cycle is transmitted from the retina to the suprachiasmatic nuclei in the hypothalamus<\/a> (R<\/a>).<\/p>\n While people differ in their cortisol rhythms, a given person tends to have consistent rhythms (R<\/a>).<\/p>\n It\u2019s also important to realize that the ratio<\/em> of cortisol to DHEA<\/a> may have various effects. These are still an active area of research [R<\/a>].<\/p>\n According to one hypothesis that has yet to be verified in humans, alterations in the circadian rhythm<\/a> of the HPA axis have been linked to the severity of autoimmune diseases (R<\/a>).<\/p>\n Researchers suggest that conditions such as autism may be linked with a dysregulated cortisol rhythm (R<\/a>).<\/p>\n Limited studies suggest that shift workers are at increased risk of several chronic diseases (R<\/a>).<\/p>\n Additionally, some breast and ovarian cancer patients have alterations in their cortisol rhythm (R<\/a>).<\/p>\n Studies in humans and animal models hypothesized a loose association between cancer and the loss of a circadian<\/a> rhythm. This rhythm is claimed to control energy balance, immune function, and other pathways that are controlled by the HPA axis. According to this experimental theory, these pathways could be involved in tumor suppression. Human data are lacking, though (R<\/a>).<\/p>\n There\u2019s still not enough evidence to draw any solid conclusions. Large, well-designed studies are needed to understand these fragmented findings.<\/p>\n Limited studies suggest that people with too low or too high cortisol may be at risk of various diseases, including cognitive-related problems.<\/p>\n However, the majority of studies covered in this section deal with associations only, which means that a cause-and-effect relationship hasn\u2019t been established.<\/p>\n For example, just because abnormal cortisol and HPA dysregulation have been linked with anxiety doesn\u2019t mean that anxiety is caused by HPA dysregulation. Data are lacking to make such claims.<\/p>\n Nonetheless, chronic stress response activation (HPA) is believed to be a causal factor of:<\/p>\n Large human studies are needed to confirm these associations.<\/p>\n Additionally, researchers suspect that lack of the hormone CRH<\/a> may result in tiredness<\/a> common to people suffering from chronic fatigue syndrome<\/a>. Lack of CRH is also thought to be central to seasonal affective disorder (SAD) – the feelings of fatigue and depression that plague some people during the winter months. More research is needed to verify this theory [R<\/a>, R<\/a>].<\/p>\n Researchers suggested that, when compared to a group of people who did not have difficulty falling asleep, insomniacs had higher ACTH and cortisol levels, both in the evening and in the first half of the night. Moreover, the insomniacs with the highest cortisol levels tended to have the greatest difficulty in falling asleep. These findings have yet to be verified (R<\/a>).<\/p>\n Diseases like diabetes have also been associated with too much HPA activation and high levels of CRH (R<\/a>). People with Alzheimer\u2019s tend to have high levels of cortisol, but it\u2019s believed to be a result and not a cause of the disease (R<\/a>).<\/p>\n In PTSD, there\u2019s a lower-than-normal cortisol release, and it is thought that a blunted hormonal response to stress may predispose a person to develop PTSD. The exact HPA axis changes that happen in PTSD are still unclear (R<\/a>).<\/p>\n<\/a>What Increases and Decreases our Stress Response?<\/strong><\/span><\/h2>\n
<\/a>Diving into the Science<\/span><\/h3>\n
<\/a>Limitations<\/span><\/h3>\n
<\/a>Daily Cortisol Patterns <\/strong><\/span><\/h3>\n
<\/a>Cortisol Circadian Rhythm<\/strong><\/span><\/h3>\n
<\/a>Rhythms of the HPA axis<\/strong><\/span><\/h3>\n
<\/a>Diseases Associated with HPA Axis Dysregulation<\/strong><\/span><\/h3>\n
\n