Stress is a natural reaction to excess demand, pressure or excitement. Hormonal and chemical defence mechanisms are triggered in your body. This is often called the 'fight or flight' reaction. It evolved to help you deal with dangerous or life-threatening situations.
You may begin to sweat. Your blood vessels to the skin constrict, muscle blood vessels swell, and the stress hormones called adrenaline and cortisol are released: adrenaline accelerates your heart rate, cortisol raises blood sugar levels.
With these changes, your body adapts itself to cope with short-term stress. It can even be enjoyable deliberately to trigger stress reactions in situations of your own choosing – playing sports, on theme park rides, taking part in the performing arts.
