Happiness has no direct effect on mortality, say experts

By Sally Robertson, B.Sc.Dec 10 2015

A study of women in the UK has shown that there is no evidence to suggest that happiness has any direct effect on reducing mortality, despite the widespread belief that being unhappy can directly cause ill health.

In fact, it is the other way around says lead author of the study:

Illness makes you unhappy, but unhappiness itself doesn’t make you ill.”

Bette Liu, University of New South Wales, Australia.

Since poor health can cause unhappiness, unhappiness has previously been associated with an increased risk of mortality. However, in the current study, the researchers found no association between unhappiness and increased mortality, even after adjusting for poor health, smoking and other socioeconomic and lifestyle factors.

As reported in the The Lancet, the findings were based on an investigation within the UK Million Women Study, which included health data for more than 700,000 women who were generally aged between 55 and 63 years.

Three years after recruitment, the women were sent a questionnaire asking them to rate their health, happiness, stress levels, feelings of control and whether or not they felt relaxed. Around one in six of the women reported being unhappy.

The researchers used the questionnaire results as a baseline to research the association between unhappiness and mortality among 30,000 of the women who died during a 10-year follow up period.

Liu and colleagues found that unhappiness was associated with smoking, deprivation, lack of physical activity and not having a live-in partner. However, the strongest association was that women who reported ill health at baseline were more likely to say they felt unhappy, stressed, not relaxed and not in control.

After adjustment for any differences in baseline health and lifestyle factors, there was no significant difference in overall death rate between women who were unhappy compared with women who were happy. As well as this being true for overall mortality, it was true for cancer mortality and heart disease mortality.

Many still believe that stress or unhappiness can directly cause disease, but they are simply confusing cause and effect,”

“Of course people who are ill tend to be unhappier than those who are well, but the UK Million Women Study shows that happiness and unhappiness do not themselves have any direct effect on death rates.”

Co-author Richard Peto, University of Oxford, UK.

The team says that previous studies claiming a link between unhappiness and mortality did not adjust properly for how strongly ill health decreases happiness.

In an associated commentary on the study, researchers from the Institute of Aging at the University Hospital of Toulouse in France call the information about happiness, health and mortality “extremely valuable and robust.” However, they emphasize the need for more studies that would look at both men and women, different cultures and different age groups.