Stress is the modern-day effect of an evolutionary mechanism known as ‘fight or flight’, designed to save our distant ancestors from dangers in the wild. For instance, when under physiological stress, our muscles may tense, blood pressure soar, the heart race and the chest hurt, as breathing becomes shallow and quick; saliva may dry up and we might sweat and shake. When these bodily changes took place for our ancestors, it was because they faced a major threat, such as a wild boar attack, and they needed to gear up to run for it or to fight for their lives. Once they had taken action, and survived, all the physiological arousal would quickly subside.

But in modern times, it is rarely a wild boar that makes us feel threatened. More often, it may be an over-demanding boss or not having enough control over our work (stress is now the most common cause of long-term sickness absence) or the demands of taking a sick relative to regular hospital appointments while trying to hold down a full-time job. The stress doesn’t end and so the physiological effects don’t ebb. That’s why we get physical symptoms from severe stress, such as disturbed sleep and ailments such as frequent migraines, backache, angina, skin eruptions, bowel problems, stomach cramps or high blood pressure.