Anxiety and depression occur when a person becomes aware that the demands of the environment are greater than his or her capacity to deal with them. When taxing events are too frequent, or prolonged, even a person with excellent coping skills will begin to experience the effects of chronic stress. At this point, stress can become a danger to one’s mental health, and if it is not dealt with, it can destroy one’s sense of well-being. Unfortunately, it appears that stress is actually increasing. In 2008, according to the American Psychological Association, 47% of adults reported a significant increase in stress since 2007.

Of those individuals who are clinically depressed, about one-half will have an excess of cortisol in their blood. Cortisol is believed to be related to clinical depression since the high levels usually reduce to a normal level once the depression disappears.

When the endocrine system is functioning properly, the hypothalamus monitors the amount of cortisol that is released by the adrenal gland. When cortisol levels rise, the hypothalamus slows down its influence on the pituitary gland by decreasing the production of CRH. Conversely, when cortisol levels drop, the hypothalamus stimulates ACTH production and the release of cortisol. However, in depressed individuals, the hypothalamus may continuously influence the pituitary to produce ACTH without regard for cortisol levels.

Other research concerning cortisol has shown that the timing of the release of this hormone may be problematic in those who are depressed. People who are not depressed tend to have secretions of cortisol at certain times of the day. Normally, cortisol levels are highest at approximately 8:00 a.m. and lowest during the night. This normal cycling of cortisol levels does not occur in some people who are depressed. For instance, they might have a consistently high or low level of cortisol throughout the day or high levels in the middle of the night.

With prolonged stress, cortisol decreases the amino acid tryptophan, which is necessary for serotonin production. Cortisol stimulates an enzyme that destroys tryptophan called tryptophan oxygenase, which leads to a decrease in serotonin production. Serotonin prevents depression and allows one to feel happy. It also has an effect on appetite, sleep, and sexual desire. Most antidepressants block the destruction and re-uptake of serotonin, which temporarily increases serotonin levels.

Elevated cortisol levels associated with prolonged stress decrease the body’s ability to make serotonin, which then initiates feelings of unhappiness. Eventually, the adrenal glands burn out and the production of cortisol declines, leading to worsening depression. When cortisol declines, the ability to mobilize glucose for energy decreases, as well. This decline leads to fatigue, impaired brain function, and further imbalance of neurotransmitters. The lack of cortisol activates the SNS, which leads to more anxiety and an inability to handle stress.