Stress and unhappiness have NO direct impact on mortality

If you're feeling a little miserable, here is something that might cheer you up.

Unhappiness won't kill you after all, according to a study – despite a long-standing consensus that the opposite is true.

For decades, doctors have believed that people who are happier and more relaxed have a better chance of enjoying good health and living longer.

 Now Oxford University scientists claim that previous research has mixed up cause and effect, meaning that stress and misery do not in themselves shorten lifespan.

'Illness makes you unhappy, but unhappiness itself doesn't make you ill,' said Dr Bette Liu from the University of New South Wales, who also worked on the study.

'We found no direct effect of unhappiness or stress on mortality.'

Professor Sir Richard Peto, from Oxford University, added: 'Worry does not kill you.

'The behaviour that worry causes could have adverse effect - like smoking or drinking. But does actual happiness itself or stress itself kill you? Then No!

The British and Australian teams looked at data from the Million Women Study, which has tracked British women since 1996.

After discounting those who were ill at the beginning of the study – published in the Lancet medical journal – they were left with 720,000 women with an average age of 59.

The participants were then asked a series of questions about how often they felt happy or stressed, before being tracked for a decade – in which time 30,000 died.

Researchers initially found a significant link between those who said they were unhappy and those who passed away.

But when they took into account smoking, lifestyle, and socio-economic factors such as wealth, they found the link disappeared.

They argue that emotions such as unhappiness or stress can cause people to take on unhealthy habits – such as smoking or drinking too much alcohol – rather than directly affecting lifespan.

Sir Richard said that although the study only looked at women, he would expect the findings to be equally relevant to men.

He added: '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 study shows that happiness and unhappiness do not themselves have any direct effect on death rates.'

He said that previous reports of reduced mortality being associated with happiness had not allowed properly for the strong effect of ill health on unhappiness and on stress.

Not all scientists, however, were convinced by the results.

Many experts - particularly heart doctors - believe that stress can cause severe damage on the body.

The study asked women ‘how often’ they feel stressed. But experts said this does not adequately take into the account the fact that stress levels can fluctuate.

Dr Lydia Poole of University College London, said: 'This research uses a very specific population, they are only looking at women who are middle aged, so how well it translates to men or other age groups is unclear.

‘It is also only self-reported, there are no measures of the cortisol stress hormone, or other biological factors.

‘There is so much evidence which shows the opposite, that I would want to see the study replicated in other samples before I could throw away everything that has gone before.’

Dr Gavin Sandercock of the University of Essex said: ‘Stress is undoubtedly bad for us, it is linked to heart disease, it is linked to some cancers and it is linked to systemic inflammation.

‘Just because you are happy “most of the time” does not mean you do not experience stress.’

He added: ‘Being happy is not a magical cure for heart disease and cancer but you are still less likely to get some diseases if you are happy. Happiness might not add many years to your life but it can certainly add some life to your later years.’

What is the 'happiness index' and how is it put together?