Shift Work

Question 1

Name 2 reasons why research into the effects of shift-work is so important

Answer 1

1) Tragedies like Chernobyl nuclear power station happened at 1:23am
2) Most lorry accidents happen between 4am and 7am

Question 2

Outline Moore-Ede (1993)

Answer 2

Estimated the cost of shift worker fatigue in the US to be $77 billion annually due to major accidents and ongoing medical expenses from shift work-related illnesses

Question 3

Name the 3 consequences of shift work

Answer 3

1) Decreased alertness
2) Sleep deprivation
3) Effects on health

Question 4

Explain decreased alertness for shift work

Answer 4

Shift workers often experience a ‘trough’ of decreased alertness during the shift between midnight (cortisol levels at their lowest) and 4am (core body temp at its lowest)

Question 5

Explain sleep deprivation for shift work

Answer 5

When sleeping in the day (noise and daylight reduces quality), typically 1-2 hours shorter and REM particularly affected - poor daytime sleep makes it more difficult for worker to stay awake, especially during the circadian trough

Question 6

Explain effects on health for shift work

Answer 6

Knutsson (1986) found shift workers for more than 15 years are 3 times more likely to develop heart disease
Martino (2008) linked shift work to a range of organ diseases

Question 7

What is the most common pattern of shifts?

Answer 7

One week on days, evenings, and nights

Question 8

Name 4 main studies associated with shift work

Answer 8

1) Czeisler (1982)
2) Reinberg (1984)
3) Soloman (1993)
4) Boivin (1996)

Question 9

Outline Czeisler (1982)

Answer 9

Introduced a forwards rotating shift to a Utah chemical plant workforce with the traditional backwards rotation (nights, evenings, and days) and after 9 months, the workers reported fewer problems and management reported increased output and fewer errors)

Question 10

What is a positive evaluative point about Czeisler (1982)?

Answer 10

It is a field study so high ecological validity

Question 11

What are 2 negative evaluative points about Czeisler (1982)?

Answer 11

1) Used self report data which is not empirical evidence so subjective
2) There are confounding variables like personality and individual differences that are not controlled

Question 12

Outline Reinberg (1984)

Answer 12

Suggested those who gave up shift work because they couldn’t cope had rhythms that changed a lot while on shifts. Whereas ‘happy’ shift workers had unchanging rhythms

Question 13

What does Reinberg (1984) show?

Answer 13

There are individual differences

Question 14

Outline Soloman (1993)

Answer 14

Looked into social disruption caused by shift work - divorce rates may be as high as 60% among all-night shift workers

Question 15

Outline Boivin (1996)

Answer 15

31 males into 4 groups for 3 days on an inverted sleep wake cycle in which they were awake at night and sleep during day. When they woke, there was 5 hours of dim light then:
1) very bright
2) bright
3) ordinary
4) very dim
After 3 days, group 1 advanced 5 hours earlier, 2 3 hours earlier, 3 1 hour earlier, and 4 drifted 1 hour later.

Question 16

What does Boivin (1996) show?

Answer 16

Room lighting can have an effect on rhythms and very bright light can have a significant effect

Question 17

What are 2 positive evaluative points about Boivin (1996)?

Answer 17

1) Supported by Boivin & James (2002) who used intermittent bright lights in a field study of nurses which confirmed effectiveness of bright lighting to promote circadian adaptation
2) Lab experiment so extraneous variables carefully controlled

Question 18

What is a negative evaluative point about Boivin (1996)?

Answer 18

Lab experiment so low ecological validity

Question 19

What is really important to note about studies investigating shift work?

Answer 19

Those willing to take part are likely to be quite motivated especially as they know that their behaviour is being monitored, so less motivated shift worker may not do so well with light therapies

Question 20

Explain about the biological approach for shift work

Answer 20

Biological approach - general laws of behaviour and studies involve large numbers of people, it makes generalisations but effects of disruption vary considerably between individuals

Question 21

What do human studies show about shift work?

Answer 21

Suggest shifts should last at least 3 weeks and should also rotate forwards (moving towards the 24 hour cycle instead of in reverse). When manual workers changed, productivity increased by 22%, leisure time more enjoyable and the health of workers improved

Question 22

Name 4 studies looking into reducing the effects of shift work

Answer 22

1) Sack (2007)
2) Bambra (2008)
3) Herxheimer & Petrie (2001)
4) Fuller (2008)

Question 23

Outline Sack (2007)

Answer 23

Naps reduce tiredness and thus increase performance

Question 24

Outline Bambra (2008)

Answer 24

Forward-rotating shifts which follow the logical order of the day may be easier on the body and less damaging to health

Question 25

Outline Herxheimer & Petrie (2001)

Answer 25

Reviewed 10 studies and found when melatonin taken near to bedtime it was effective but if taken at the wrong time, might actually delay adaptation

Question 26

Outline Fuller (2008)

Answer 26

Social customs help to entrain rhythms, e.g. eat at right time as some body clocks reset by food intake

Question 27

Name 2 IDA points about shift work

Answer 27

1) The biological approach

2) Real-world application

Question 28

Explain the real-world application for shift work

Answer 28

We can use artificial lighting to entrain and reset rhythms, thus helping us to avoid disasters