The concept of "stress" is not strictly defined within any academic field, or uniformly understood by the general public. Many people regard it as a meaningless catch-all term, or simply as something that doesn't exist at all. But in recent years it has become increasingly clear that psychological factors in a person's life which can be reasonably regarded as "stressful" have a negative impact on mental and physical health. You could call this banal, or say that it merely harks back to old pre-Dualist ideas about the necessity of a healthy mind for a healthy body. But recent research puts properly controlled, operationalized, empirical evidence in support of the case that stress is bad for your health.

"Health inequalities among British civil servants: the Whitehall II study" was a longitudinal epidemiological study carried out by a group of researchers in 1985, in follow-up to an earlier, smaller scale Whitehall I study. The aim was to investigate the link between work conditions and self-reported ill-health among the participants, 10,000 civil servants employed at Whitehall in London. The hypothesis, of course, was that stressful work conditions would correlate with ill-health.

The psychological effect of the work environment was rated in terms of four factors: Decision latitude (essentially degree of control), job demands (e.g. pace of work and conflict between competing tasks), social support from supervisors and colleagues, and effort-reward imbalance.

Ill-health was also rated in terms of four factors: alcohol dependence, mental health, health functioning (general health), and increase in sickness absence.

The results were clear. The following table and written summary are taken from

Work characteristic:               Associated with:

Low decision latitude              -alcohol dependence
                                   -poor mental health
                                   -poor health functioning
                                   -more sickness absence

High job demands                   -poor mental health
                                   -poor health functioning

Low social support at work         -poor mental health
                                   -poor health functioning
                                   -more sickness absence

High effort, low reward            -alcohol dependence
                                   -poor mental health
                                   -poor health functioning
                                   -more sickness absence

"Low decision latitude, low work social support, high work demands, and effort-reward imbalance were associated with poor general mental health in men and women. In men, low decision latitude, high job demands, low work social support, and effort-reward imbalance were related to increased risk of poor social functioning at follow-up. The results, apart from decision latitude, were similar in women."
In short, if your job is stressful, you're more likely to become mentally or physically ill.

Here is an example of some of the questions the participants had to answer (these relate to "skill discretion"):

  • Do you have to do the same thing over and over again?
  • Does your job provide you with a variety of interesting things?
  • Is your job boring?
  • Do you have the possibility of learning new things through your work?
  • Does your work demand a high level of skill or expertise?
  • Does your job require you to take the initiative?
The conclusions of the study are quite interesting. Your experiences at work affect not only your mental health, but your physical health and your ability to function socially.

In short, optimistic people in control are physically healthier than pessimistic ones with a stressful life. Matt Ridley has put it like this: "...even if the permanent secretary was fat, hypertensive or a smoker, he was still less likely to suffer a heart attack at a given age than a thin, non-smoking, low-blood-pressure janitor...Far from behaviour being at the mercy of our biology, our biology is often at the mercy of our behaviour."