If the stimulus is mild or perceived as non-threatening, then there is little hormone release and we react in a healthy fashion. An example of positive stress is when you get a job promotion or move to a new home. At times however, excess stress-creating stimuli may overwhelm our abilities to respond and cause a negative effect, often called 'distress'. In this case, the stimuli may present either a 'real' or 'perceived' threat to us. The body responds immediately, pouring out hormones, which result in increased heart rate, blood pressure, and breathing, as well as sweaty palms and cool, clammy skin.
Stressful events can also trigger emotional feelings of anxiety, fear, insecurity, and anger.
For most people, brief stressful encounters are well tolerated. Prolonged stress, however, has been linked to many health problems including sleep disturbances, ulcers, high blood pressure, heart disease, stroke, and depressed immune function. Scientists have been researching the effects of stress on illness for over fifty years. Many studies have shown a link between chronic stress and impaired immune system function. Researchers believe that chronic stress affects the immune system in a number of ways.