What is stress?
Stress is what we feel when our bodies are under strain. Stress keeps us alert and ready for action, enabling us to respond quickly when needed and adapt to change. A limited amount of stress is stimulating and rewarding - it enables us to meet important demands, perform well under pressure, achieve life goals and experience great excitement. In fact, stress is a normal physiological response when the adrenal glands are activated and they release the hormones adrenaline and cortisol into the blood. Chronic stress refers to the situation when the adrenal glands are stimulated for a prolonged period, at which point beneficial effects of stress hormones are lost. Persistently high cortisol levels can have a detrimental impact on many physiological processes.
Why is stress important?
To many people stress is simply part and parcel of leading a busy life. These individuals enjoy multi-tasking, thrive under stimulation and show a high level of stress resilience. In others, too much stress is debilitating and leaves them feeling unable to cope. What makes some people stress vulnerable is not well understood, but we know that too much stress is associated with absenteeism from work and is a major risk factor for the development of health problems such as heart disease, stroke, obesity, irritable bowel disorder, infertility, cognitive impairment and depression. Stress disorders affect people of all ages, young and old, and research aims to improve understanding of the processes involved in stress, vulnerability factors and the control of stress hormone release. We need to understand stress better so that we can improve the quality of life of those currently suffering, and to prevent development of stress-related diseases in the future.
How does the stress response work?
The adrenal glands are tightly regulated in all mammals. Many factors control release of the stress hormone, cortisol, via actions in the brain, particularly in the paraventricular nucleus of the hypothalamus, and appear to play important roles in controlling ways in which our bodies respond to stress. Release of cortisol is precisely controlled by hormones made in the hypothalamus and pituitary gland resulting in a daily, rhythmical secretion of cortisol that is highest first thing in the morning and lowest in the evening. How the brain actually interprets the stress signal and appropriately coordinates the pituitary and adrenal response is known to be dependent on the type and duration of the stressor. However, there are multiple factors involved in shaping an individual stress response and working out the involvement of each of these is an area of intensive research. Attention has focussed on interactions between social, environmental and genetic factors. Gender is relevant too since stress-related psychiatric conditions are more common in women than men.