Stress can be caused by many things including; severe negative emotional shocks (death in the family, divorce, family problems, financial setbacks, etc.), overworked and run down over an extended period of time, lack of rest and moving house; they all contribute to a weakening of the immune system.
This immunosuppressant effect is responsible for the onset of many diseases including cancer. A cancer researcher in the US who consulted with over 30,000 cancer patients concluded that most of the cancer patients he spoke with had a major stress in their life six months to three years before they were diagnosed with cancer.
A recent study  reveals how stress influences disease, identifying inflammation once again as the culprit. Stress and anxiety wreak havoc on the mind and body. For example, psychological stress is associated with greater risk for depression, heart disease and infectious diseases. But, until now, it has not been clear exactly how stress influences disease and health.
The research team found that chronic psychological stress is associated with the body losing its ability to regulate the inflammatory response, which demonstrated for the first time how this leads to the development and progression of disease.
Inflammation is partly regulated by the hormone cortisol and when cortisol is not allowed to perform this function, inflammation can spiral out of control because it decreases tissue sensitivity to the hormone; specifically, immune cells become insensitive to cortisol's regulatory effect, leading to chronic inflammation; the precursor for many diseases.
Earlier ground breaking research work showed that people suffering from psychological stress are more susceptible to developing common colds. With the common cold, symptoms are not caused by the virus; rather they are a side effect of the inflammatory response that is triggered as part of the body's effort to fight infection. The greater the body's inflammatory response to the virus, the greater is the likelihood of experiencing the symptoms of a cold.
The immune system's ability to regulate inflammation predicts who will develop a cold, but more importantly it provides an explanation of how stress can promote disease. When under stress, cells of the immune system are unable to respond to hormonal control and consequently produce levels of inflammation that promote disease. Inflammation plays a role in many diseases such as cancer, cardiovascular, asthma and autoimmune disorders (type one diabetes, Addison's disease, Sjögren's syndrome, rheumatoid arthritis and autoimmune thyroid disease).
Increased levels of cortisol caused by chronic stress also plays a role in hormonal and metabolic reactions that lead to susceptibility to female cancers and weight gain by increasing oestrogen and impairing glucose metabolism by reducing insulin function, in turn increasing fat storage, your appetite and cravings for unhealthy foods. Couple this with the fact that stress lowers your willpower (by draining brain energy) making it more difficult to resist temptation to these unhealthy foods. This cascade type scenario is also a result of lack of sleep.
Cortisol also reduces testosterone in men and women, which leads to muscle loss. Muscle burns more calories than body fat. When you lose muscle, your body burns calories less efficiently. Also, cortisol increases fatigue, which makes it more likely that you won't exercise to burn off excess calories.
Tips to reduce your stress and cortisol levels
Practice deep breathing - is perhaps the best way to reduce your stress levels and put you in a calmer state of mind. Find somewhere quiet to sit and breathe in and out deeply for ten to twenty breaths.
Several studies have also shown that deep breathing can treat eating disorders and obesity. These studies have also shown that there are a lot of patients who have an abnormal concentration of carbon dioxide in their blood, causing them to tire easily because of disrupted tissue function. This shows that people who do deep breathing are more energetic and can handle more physical activities as well as being less prone to depression which leads to eating disorders and obesity.
Supplements - fortunately there are adaptogens that can blunt the secretion of excess cortisol including; Rhodiola, Ashwagandha, Vitamin B6, Vitamin C, Zinc, Pantothenic acid and Schisandra.
Speak to your doctor about trying DHEA, which can lower plasma cortisol levels in men and women, according to a University of Pittsburgh study published in the Journal of Clinical Psychopharmacology in February 2003.
Limit coffee - excess coffee consumption causes cortisol secretion and it's not just about the caffeine; there are other compounds in coffee that contribute to this.
Exercise - any type of exercise will help alleviate cortisol levels, unless it is excessive or chronic cardio causing the reverse.
Sleep - I have to stress the importance of sleeping well. Dedicating at least seven to eight hours of sleep each evening will go a long way towards improving your mental outlook and making you feel like you can handle problems and temptations that come your way by increasing your willpower and self-control.
Those who aren't sleeping enough are more likely to have higher cortisol levels as well, so this is something that you do really have to watch.
Getting enough sleep also makes a difference. Just two nights of good, sound sleep can be more effective at reducing cortisol than a lifetime of stress management classes.
Yoga - is another great way to reduce stress and cortisol levels. It focuses on bringing you a better overall mind-body connection and can help you feel more relaxed and energised as you go about your day.
Yoga is available in many different varieties, so check out a few class offerings.
Start a journal - writing a journal is the next way to combat stress and reduce your cortisol levels. Getting your thoughts and feelings down on paper can help you place them out of mind so you aren't as likely to ruminate over them again and again.
Journaling is a technique that far too many people overlook as being effective but can really enhance the way that you feel.
Get Support - having a high level of interpersonal support is the next way to combat stress and reduce cortisol. Whether you turn to a close friend for support or your husband or wife or possibly even a therapist, find someone who you can talk to during the hard times. They can be your best ally for busting through stress.
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 Sheldon Cohen, Denise Janicki-Deverts, William J. Doyle, Gregory E. Miller, Ellen Frank, Bruce S. Rabin, and Ronald B. Turner. Chronic stress, glucocorticoid receptor resistance, inflammation, and disease risk. PNAS, April 2, 2012 DOI: 10.1073/pnas.1118355109