Adrenal Fatigue is a term applied to a set of non-specific symptoms that include fatigue and extreme tiredness, weak immune system, depression, anxiety, brain fog, low blood sugar, low libido, waking up tired even after 7 or 8 hours of sleep, cravings for sugary or salty foods and trouble sleeping through the night (especially waking up between 2-4am). Though Adrenal Fatigue appears in popular functional medicine books and alternative medicine circles, there is little evidence to support its existence and it is not accepted as a legitimate medical condition.

Background of Adrenal Glands

The theory behind Adrenal Fatigue is largely based on the work of researcher Hans Selye who proposed that the body goes through 3 phases when exposed to chronic stress ultimately leading to shut down or system-wide failure. The 3 phases are generally described as follows:

1)     Alarm reaction – the body’s initial response to heightened stress levels(fight or flight), which involves the adrenal glands producing lots of cortisol.
2)     Resistance – Long term stress or when stress is prolonged, the adrenal glands struggle to keep up with cortisol production and levels may be normal or high.
3)     Exhaustion – at this stage the adrenals are “fatigued” and can no longer produce enough cortisol to keep up with demands and Cortisol levels dip.

Though this might sound logical there is no evidence to support this theory. In fact, the Endocrine Society (which represents 14,000 endocrinologists) has put out a public statement that reads:

“‘Adrenal Fatigue’ is not a real medical condition. There are no scientific facts to support the theory that long-term mental, emotional, or physical stress drains the adrenal glands and causes many common symptoms.”

In an exhaustive study of all the research related to chronic stress and Cortisol levels it was found that there was no correlation between the two. The majority of studies show no significant differences in levels between people experiencing high vs low stress. There is no clear pattern of chronic stress being associated with low Cortisol levels. Even when disorders such as Burnout Syndrome, Vital Exhaustion (or Exhaustion Disorder) and Chronic Fatigue Syndrome/Fibromyalgia (which have very similar symptoms to Adrenal Fatigue) were studied, it was found that these disorders were NOT reliably associated with low Cortisol levels. Some studies show slightly higher cortisol ^{1 2}, some show lower ^{3 4} and some show no difference ^{5 6 7}.

If anything, the overall literature shows that both acute and chronic stress is characterized by higher (not lower) cortisol levels  ⁸. For an in-depth examination on the literature on how different chronic stressors affect levels see “Debunking Adrenal Fatigue”

Recent prospective cohort studies also suggest that “there are no HPA axis* changes present during the early stages of the genesis of fatiguing illnesses” ⁹, thus confirming that it cannot be the cause. The same study also suggests “a reversed direction of causation (ie that the illness leads to HPA axis change rather that the other way around) is supported by the findings that there is an apparent absence of HPA Axis changes early in the genesis of chronic fatigue states, and that modifying cognitive behavioral components of the illness leads to normalization of the HPA axis.” ¹⁰

Symptoms of Adrenal Fatigue

• weight gain
• lack of sex drive
• lightheadedness
• craving salt and sugar
• bone loss/osteoporosis
• poor immune function
• sleep problems/insomnia
• acne and other skin problems

Cortisol abnormalities that do occur in a subset of people with chronic fatigue can easily be explained by lifestyle and behavioral factors such as inactivity, sleep disturbances, psychiatric comorbidity, medication and stress. One study concluded that “the changes observed in CFS may be secondary to disrupted sleep and social routine, and thus an epiphenomenon** in terms of fatigue causation.” ¹¹

You can read a comprehensive debunking of the idea of adrenal fatigue by reading the article “Is Adrenal Fatigue Real?”

What is Adrenal Insufficiency

Though a blood test is not a valid way of assessing symptoms of adrenal fatigue, it is useful for ruling out legitimate medical conditions such as Addison’s Disease (also called Adrenal Insufficiency), in which there is a pattern of high ACTH and low levels (which indicates that the brain is directing the adrenals to release more Cortisol but the adrenals are unable to produce enough). 

Addison’s disease occurs in all age groups and both sexes, and can be life-threatening. Signs and symptoms include: extreme fatigue, weight loss and decreased appetite, darkening of your skin (hyperpigmentation), low blood pressure, fainting, salt craving, low blood sugar (hypoglycemia), nausea, diarrhea or vomiting (gastrointestinal symptoms), abdominal pain, muscle or joint pains, irritability, depression and body hair loss or sexual dysfunction in women. ¹² Treatment for Addison’s Disease involves taking hormones to replace those that are missing.

Other Potential Causes of Fatigue

Symptoms such as being tired, lacking energy, and sleeping all day long could be signs of depression ¹³, fibromyalgia, or any number of diseases. In addition, low morning Cortisol could be due to a flattened diurnal curve of Cortisol, whereby less Cortisol is produced in the morning and more produced in the night. This occurs for a number of reasons including:

1. Staying up late at night (ie. being a night owl) ^{14 15 16}
2. Lack of morning light exposure ^{17 18 19}
3. Night eating ²⁰
4. Being overweight ²¹
5. Nutrient deficiencies (including deficiencies of Vitamin C, B Vitamins, Folic Acid, Panthenoic Acid, Biotin, Calcium, Potassium, Zinc and Iron) which can be corrected with multivitamin supplements ²²
6. Rumination and neuroticism (which both contribute to depression ²³
7. Helplessness, hopelessness and low self-esteem ^{24 25}
8. Cynicism ²⁶
9. Taking certain medications, such as anti-depressants ²⁷, Aspirin ²⁸, Tylenol (acetominaphen) ²⁹, Opiods ³⁰ and some blood pressure lowering drugs ³¹
10. Recent loss of a partner and/or social isolation ³²
11. Ethnicity – African Americans and Hispanics tend to have lower morning Cortisol levels than Caucasians ³³
12. Low physical activity levels ³⁴
13. Anticipation of a low stress day/vacation ³⁵
14. Lower socioeconomic status ³⁶
15. Psychological trauma or PTSD (post-traumatic stress disorder) ³⁷
16. Genetics – different groups of people have different baseline cortisol levels that can be inherited ^{38 39}
17. Toxins – such as glyphosphates, fungicides, BPA found in plastics and heavy metals have been shown to interfere with blood cortisol levels ^{40 41 42}
18. Inflammation – resulting from oxidative stress can cause the body to intentionally suppress Cortisol levels ⁴³
19. Poor sleep ^{44 45} – this can be from not insufficient sleep duration or quality (resulting from conditions such as sleep apnea) or simply from poor circadian rhythm and sleep hygiene habits that result in poor sleep efficiency.

This shows that Cortisol output changes dynamically with whats going on day-to-day and is not a stable diagnostic of “adrenal fatigue”. Morning Cortisol is most influenced by sleep quality and duration and one study concluded that “Neuroendocrine abnormalities (ie low morning Cortisol) reported to be characteristic of Chronic Fatigue Syndrome may be merely the consequence of disrupted sleep and social routine.” ⁴⁶

In essence, if you do have low levels (as shown from a valid test) you can fix the factors that cause low morning cortisol and improve your symptoms!

Conclusion

In conclusion, it can be said that there is no evidence to explain the cause of chronic fatigue through the theory of adrenal exhaustion or low cortisol levels and if we are going to find effective answers to chronic fatigue, we must let go of these outdated theories and look for alternative causes.

*  the HPA Axis refers to the important hormonal response system—the hypothalamic–pituitary–adrenal (HPA) axis—which produces the stress hormones known as glucocorticoids and primarily cortisol. The action of this hormone system is to tightly regulate the body’s response to stress and bring it back to homeostasis.

** a secondary symptom, occurring simultaneously with a disease or condition but not directly related to it.