Stress is the way that you feel when pressure is placed on you.
A little bit of pressure can be productive, give you motivation, and help you to perform better at something. However, too much pressure or prolonged pressure can lead to stress, which is unhealthy for the mind and body.
Everyone reacts differently to stress, and some people may have a higher threshold than others. Too much stress often leads to physical, mental and emotional problems.
In the UK, anxiety and depression are the most common mental health problems, and the majority of cases are caused by stress. Research by mental health charities also suggests that a quarter of the population will have a mental health problem at some point in their lives.
Stress chemicals
When faced with a situation that makes you stressed, your body releases chemicals, including cortisol, adrenaline and noradrenaline. These invoke the 'fight or flight' feelings that help us to deal with the situation. However, when you're in a situation that prevents you from fighting or escaping, such as being on an overcrowded train, these chemicals are not used.
If the chemicals that are released during stressful situations accumulate from not being used, their effects are felt by the body. A build-up of adrenaline and noradrenaline increases blood pressure, heart rate, and the amount that you sweat. Cortisol prevents your immune system from functioning properly, as well as releasing fat and sugar into your blood stream.