Stress is the by-product of stressor triggers (e.g. an argument, an irritating encounter, an accident), which your body identifies and triggers a surge in hormones to help you deal with the pressure until you feel more comfortable - if the stress remains the hormone levels remain high. This can lead to anxiety, moodiness and irritability, sleeping problems, weight gain or loss of appetite, irrational behaviour or decision making, and physical illness such as sickness, headaches and muscle pain.