London - Happiness may make the world go round but it does not make you live longer, according to new research that challenges the widespread belief that stress leads to ill-health.
A 10-year study of one million women found people's emotional wellbeing had no direct effect on mortality. Previous research linking happiness with health simply confused cause and effect, the researchers claim. Life-threatening poor health causes unhappiness, which is why unhappiness is associated with increased mortality.
The study is so large that it rules out unhappiness being a direct cause of any material increase in overall mortality in women.
Smoking usually made people unhappier than non-smokers, researchers found. However, after taking account of previous ill health, smoking, and other lifestyle and socio-economic factors, they found that unhappiness itself was no longer associated with increased mortality.
Co-author Professor Sir Richard Peto, of the University of Oxford, said: “Many still believe that stress or unhappiness can directly cause disease, but they are simply confusing cause and effect. Happiness and unhappiness do not themselves have any direct effect on death rates.”
The investigation, published in The Lancet, was carried out within the Million Women Study - a national study of women's health, involving more than one million UK women aged 50 and over, and a collaborative project between Cancer Research UK and the NHS.
Three years after joining the study, women were sent a questionnaire asking them to self-rate their health, happiness, stress, feelings of control, and whether they felt relaxed.
Lead author of the research, Dr Bette Liu, now at the University of New South Wales, Australia, said: “Illness makes you unhappy, but unhappiness itself doesn't make you ill. We found no direct effect of unhappiness or stress on mortality.”
The effects of happiness and wellbeing on society are becoming increasingly studied, with the British government introducing its Happiness Index in 2012 to measure national well-being.
The Independent