The connection between emotional and physiological responses is well established. The amount of research conducted over decades on the effects of stress on the human body and the role of serotonin in regulating mood have conclusively demonstrated that emotional responses trigger physiological reactions, and that imbalances in certain chemicals produced in the body, like serotonin, affect emotions. For example, it has long been known that serotonin is produced in both the brain and in the digestive system, which helps explain the connections between mood and appetite and between anxiety or stress and gastrointestinal disorders. The presence of this particular chemical in the digestive system has been definitively linked to incidences of intestinal irritability (or “irritable bowel syndrome”) in individuals suffering from anxiety or depression. Similarly, stress-related headaches are a common feature in many peoples’ lives, as both chemical reactions in the brain and the tightening of muscles of the head and neck cause discomfort directly associated with emotional responses to external stimuli. Most importantly, as the following quote from the Johns Hopkins School of Medicine website states, emotional responses can also be directly linked to life-threatening illness:
“Stress cardiomyopathy, also referred to as the “broken heart syndrome,” is a condition in which intense emotional or physical stress can cause rapid and severe heart muscle weakness (cardiomyopathy). This condition can occur following a variety of emotional stressors such as grief (e.g. death of a loved one), fear, extreme anger, and surprise. It can also occur following numerous physical stressors to the body such as stroke, seizure, difficulty breathing (such as a flare of asthma or emphysema), or significant bleeding.” [http://www.hopkinsmedicine.org/asc/faqs.html]
There is another, more tenuous link between emotions and illness that could be included in this discussion. This involves the more subtle degradation in the body’s immune system caused by protracted periods of stress or agitation. Once the body’s natural immune system is weakened, it becomes vulnerable to all matter of infections, including deadly ones. The Mayo Clinic, one of the most highly respected medical facilities in the world, notes the connection between mental well-being and physical health. With respect to the hormone cortisol, the Clinic has this to say regarding stress and the human immune system:
“Cortisol also curbs functions that would be nonessential or detrimental in a fight-or-flight situation. It alters immune system responses and suppresses the digestive system, the reproductive system and growth processes. This complex natural alarm system also communicates with regions of your brain that control mood, motivation and fear.” [http://www.mayoclinic.org/healthy-living/stress-management/in-depth/stress/art-20046037]
With respect to verification of findings, all of the information provided above is the result of extensive research utilizing animal and human subjects as well as computer simulations. By subjecting test subjects to conditions normally associated with fear, stress, sadness, etc., physicians and scientists can, through both invasive and external observations, determine the body’s reaction to these conditions. Blood tests, for example, can demonstrate elevated or depressed levels of certain chemicals or hormones, and brain scans can allow scientists to observe the brain’s reaction to external stimuli. Consequently, the connections between physiological and emotional states have been proven.
The connection from physiological and emotional responses is in fact a very strong connection. According to psychologists Cannon-Bard, James-Lange, and Schacter-Singer, we can see how interconnected these two responses actually are. These psychologists theorized that either emotional responses causes physiological responses, physiological responses causes emotional responses, both physiological responses and emotional responses occur simultaneously, or there is a cognitive label on these responses.