The intimate links between health and happiness

Good physical health appears to contribute to happiness, while happiness appears to contribute to good physical health

Is there a link between physical health and happiness? If so, how strong is the association and what can we do to optimise the benefits that good physical health can bring to our sense of mental wellbeing and that of our patients?
Perhaps the first issue to address is the extraordinary tendency to regard physical and mental health as somehow separate from each other. I am continually intrigued by the tendency to regard mental wellbeing as entirely separate from physical wellbeing. When pressed, many people agree that there is a link between the body and the mind, but most stop short of regarding physical and mental wellbeing as simply two sides of the same coin.

This is a pity. Each of us is a single, unified, embodied organism. It is helpful if we maintain an awareness of this fact and avoid drifting into the false belief that our mental life is significantly separate from our physical one. It is not.
That said, what does recent research tell us about the relationship between physical wellbeing and mental health, psychological wellbeing and happiness?

One analysis of the National Survey of American Life examined the association between happiness and self-rated physical health among African-American men and found that men who report being happy also report better physical health (American Journal of Men’s Health 2018; 12: 1615-20). Analysis of the World Values Survey from 15 countries across five continents confirms that poor health is strongly associated with unhappiness and dissatisfaction right around the world (Journal of Socio-Economics 2006; 35: 348-65).

Interestingly, a growing body of research examines the idea that reduced happiness is not only a consequence of ill-health, but might also contribute to poor health in the future. In other words, the relationship between ill-health and unhappiness might work either or both ways, with ill-health causing unhappiness, unhappiness causing ill-health, or each causing the other to varying degrees.

How might happiness or unhappiness affect health? There are several potential mediating links including physical activity, dietary choices, and a range of biological processes possibly linked to inflammation and hormones. Some of the research on these themes is inconsistent, but it is increasingly difficult to deny the growing body of evidence that links happiness today with physical wellbeing in the future, supporting the idea that happiness predicts future health.

One 2015 study reported findings from 9,050 older adults in the English Longitudinal Study of Ageing who were followed up for an average of 8.5 years to see if eudemonic wellbeing (finding meaning and purpose in life) is associated with better future health (Lancet 2015; 385: 640-8). The average age of participants in this study was 65 years. Researchers divided the group into four quarters based on wellbeing and found that 29 per cent of people in the quarter with the lowest level of wellbeing died during the follow-up period, compared to just 9 per cent of those in the quarter with the highest level of wellbeing.

While these results do not prove that wellbeing causes better health and a longer life, they suggest that a high level of wellbeing is associated with good health in the future, and not just in the present or the past. Other studies support these ideas. Happiness and life satisfaction are also linked with the absence of long-term, limiting health conditions and higher physical health levels in future years.

At this point, then, we can answer the question of whether there is a link between physical health and happiness by confirming that such a link exists and probably works both ways: Good physical health appears to contribute to happiness and happiness appears to contribute to good physical health. Possible links between subjective wellbeing and good physical health include cardiovascular mediators, immune modulators, various hormones, genetic factors, wound healing, and health behaviour.

Owing to these close associations, it is not surprising that certain activities and lifestyle choices contribute to both physical health and happiness, albeit possibly at different times and in slightly different ways. Diet is a good example. One study looked at wellbeing and happiness after increases in consumption of fruit and vegetables by examining the food diaries of 12,385 Australian adults (American Journal of Public Health 2016; 106: 1504-10). These researchers found that increased consumption of fruit and vegetables was associated with enhanced happiness, life satisfaction, and wellbeing over the following two years.

We already know that healthy foods are associated with better physical health, but those benefits can take decades to accrue, so it might be useful to show people evidence of the happiness gains from a better diet – gains that occur sooner than the physical health benefits, which can seem quite distant. In other words: Happy today, healthy tomorrow!

Brendan Kelly is Professor of Psychiatry at Trinity College Dublin and author of The Science of Happiness: The Six Principles of a Happy Life and the Seven Strategies for Achieving It (Gill Books)