The mind and body act on each other in remarkable ways. Recent research indicates that the immune system is in direct contact with and under at least partial control of the part of the brain physiologically reactive to emotions. Thus there may be a biological link between emotions and disease and even death. Mortality is three times higher in individuals with few close relationships, whereas people with strong support groups have additional protection against life stressors. Death rates are higher for cancer patients with pessimistic attitudes. Illness is more common among people who feel locked into strife-ridden marriages. Conversely, AIDS patients with healthy psyches seem better able to withstand disease.

Any stressful situation takes its toll on the human body. Stress can be a primary enemy of overall health and a major contributor to disease. Because stress affects the immune system, the body becomes more susceptible to a multitude of ailments, from colds to cancer. Respiratory conditions, such as asthma, may become worse. The cardiovascular system reacts by constricting the blood vessels while increasing blood volume. The net result is a rise in blood pressure throughout a stress-ridden day. Multiple increases in blood pressure can eventually contribute to chronic high blood pressure. More forceful contraction of the heart elevates levels of free fatty acids, enhancing the development of clogged arteries leading to and including the heart itself. In extreme cases, sudden death can occur, especially if an individual has been experiencing high levels of uncontrolled stress for an extended period.

Headaches, including migraines, have long been associated with stress. Tension headaches are caused by involuntary contractions of the scalp, head, and neck muscles. Typical muscular reaction to stress is contracting or tensing. When chronic stress occurs, the body reacts by being constantly ready to respond and the muscles become braced, or always in a state of tension. More stress magnifies the tension the muscles are already undergoing. Increased muscular tension manifests itself in headaches, backaches, neck aches, and other pains. The smooth muscles that control internal organs also experience pains. More intense contractions can lead to stomach ache, diarrhea, hypertension, heartburn, gastritis, diarrhea, bloating, inflammation of the pancreas, and blockage of the bile ducts

Stress decreases saliva in the mouth, often making speaking awkward. Swallowing may become difficult, and the increase in stomach acids contributes to ulcer pain. People tend to perspire more, and electrical currents are transmitted more quickly across the skin. Skin conditions, such as acne, psoriasis, herpes, hives, and eczema, are exacerbated.

Stress also seems to affect the body's nutritional status and immune response to disease. Individual nutritional patterns can also influence stress management efforts. For example, eating too much or too little, eating the wrong kinds of food, and overusing products such as caffeine or alcohol upset homeostasis. Diets high in fat, sugar, and processed foods place a heavy burden on various body systems. Ingesting too few calories can lead to the breakdown of lean tissue. To meet the demands of stress, you should maintain adequate nutrition through a balanced and varied diet.

Ultimately, no body system escapes the effects of stress. Long-term presence of certain stress­associated hormones in the brain damages receptors and cells found in the hippocampus. (The hippocampus sends messages when stress is occurring.) Because brain cells do not regenerate, these cells are lost forever. The effects of this loss are unknown, but indications are that eventually humans become less able to respond to stress appropriately provides guidelines for identifying stress style and suggests relaxation activities.