Stress Studies

Procedure

- 75 medical students
- Blood samples taken one month before exam (low stress) and during exams (high stress)
- Questionnaire on negative life events and social isolation

Findings

- Natural killer cell activity reduced in high stress situation blood samples
- High level of social isolation reduced natural killer cell activity in high stress situations

Conclusion

- Exam stress (naturalistic stressor) reduces immune function- more vulnerable to illness
- Effects of stress & illness is more noticable when experiencing high levels of isolation

Strengths

- Hardly any ethical issues - high mundane realism - high eco validity - generalise

Weaknesses

- Blood sample may cause stress itself - unrepresentative sample - cannot generalise

Procedure

- 394 participants - questionnaire on stressful events in previous year
- Rated degree of stress - rated level of negative emotions
- 3 scores combined = stress index score
- Participants exposed to common cold

Findings

- 82% infected by virus
- After 7 days, the number of people whose infection developed into a clinical cold was recorded and showed that the chance of developing symptoms of a cold due to failure to fight infection was positively correlated to stress index score

Conclusion

- Life stress and negative emotions reduce the effectiveness of our immune system - less able to resist viral infection

Strengths

- Shows strong relationship between stress and illness

Weaknesses

- Indirect study - no measure of immune function
- Doesn't tell us which part of the stress index is most important
- Ethical issues - made participants purposely ill

Procedure

- 394 USA participants
- Compare 42 life events giving each a LCU between 0-100 = 100 most stressful
- Marriage had central value of 50

Findings

- Score over 300 doubles risk of illness

Conclusion

- Stress load is cumulative so many events in a period of time would cause a more stressful experience

Weaknesses

- Ethnocentric - evaluating all cultures from one culture - assumes life events cause stress - retrospective reports may be unreliable  - vague/subjective - individual differences not taken into account

Procedure

- Prospective study
- 2500 healthy male USA navy personnel
- Filled in SRRS for previous 6 months giving LCU
- Followed up over the following 7 months
- An illness was recorded and rated for number and severity producing an illness score

Findings

- Weak positive correlation of 0.118 between LCU and illness score
- Relationship between life events and development of stress related illness
- Low correlation = other factors have to be involved

Weaknesses

- Unrepresentative sample - results are gender, culture and occupationally specific - cant generalise - lacks population validity - correlation cannot show cause and effect - EVs - lacks validity

Procedure

- Hassles scale of 117 events and then 135 uplifts (counteract hassles)
- Hassles and uplift scale, symptoms scale and life events scale given to 100 Californian WASPS
- Completed it each month for 9 months except for life events scale which they completed once after 10 months

Findings

- Strong correlation between hassles and illness which was stronger than the correlation between life events and illness (supported by Delongis)
- Women's biggest hassle is weight gain

Conclusion

- Hassles are more significant for health than life events

Strengths and Weaknesses

- Repeated measures design - no individual differences - valid comparison HOWEVER demand characteristics - less internal validity - order effects - unreliable

Procedure

- London based government civil servants

Findings

- Clear differences found between workers and heart problems and mortality rates
- Workers in lower paid grades had twice the illness rate of workers in higher paid grades
- Difference in risk factors (e.g. lower paid grade workers smoke more, high blood pressure) accounted for 1/4 of the difference meaning 3/4 is due to stress

Strengths

- Many studies support findings

Weaknesses

- Largely bias - self report studies - social desirable answers - sample was bias and unrepresentative - findings hard to generalise - lacks validity

Procedure

- London based government civil servants
- Analysed data from over 7000 participants all with no heart problems to begin with
- Followed up over 5 years

Findings

- Data showed similiar differences to Whitehall 1
- Rate of illness in lower paid grade is 1.5 times the rate in higher paid grade
- Risk factors (smoking etc) could only account for some differences
- Most significant factor was the decision latitude or control participants felt they had

Strengths and Weaknesses same as Whitehall 1 study

- Also, Larger sample size - more reliable

Procedure

- 24 workers at a Swedish sawmill
- High risk group of 14 workers who had complex jobs and had to work at a set pace - responsible for team's wages. Control group was 10 workers/cleaners/maintenance
- Daily urine samples when arrival at work then 4 times during the day to measure adrenaline
- Body temperature recorded at time of collection
- Self-reports of mood, alertness, caffeine and nicotine consumption
- Self-rating scales of words such as sleepiness, irritation and wellbeing
- Baseline measurements taken at same times when workers were at home

Findings

- High risk control group = adrenaline levels 2x as high as baseline measurements - increased
- Control group had a peak level of 1.5 times baseline measurement - decreased during day
- In self-report, high risk group felt more rushed and irritated than control group
- High risk group rated their well-being lower than control group

Conclusion

- Repetitive machine paced work which was demanding in attention to detail and was highly mechanised contributed to the stress levels in the high risk group

Weaknesses

- Small sample size - occupation and culture bias - unrepresentative to whole population therefore findings are hard to generalise

- Didn't take into account all risk factors such as obesity and genetics etc

Procedure

- 3145 middle aged men from USA
- Structured interview to determine Type A or Type B personality based on respones and behaviour e.g. tapping and speech pace
- Followed for 8.5 years

Findings

- 257 heart attacks which 69% were type A
- Type A individuals more vulnerable to disease

Strengths

- High ecological validity - no ethical issues

Weaknesses

- Culture and gener specific - unrepresentative - hard to generalise - EVs - unreliable - subjective personality type determination

Procedure

- Questionnaires to assess contol, commitment and challenge to male white collar workers

Findings

- Found people with high scores on these elements reported fewer symptoms of stress

Conclusion

- High levels of hardiness protect against harmful effects of stress
- Type A less vulnerable to effects of stress than originally thought - competitiveness involved with commitment and challenge

Strengths

- Supported by later studies

Weaknesses

- Lacks eco validity - all male sample - bias - assumptions - hard to generalise